geosciences

Article Imaging Buried Archaeological Features through Ground Penetrating Radar: The Case of the Ancient (, )

Marilena Cozzolino * , Vincenzo Gentile, Claudia Giordano and Paolo Mauriello

Department of Human, Social and Educational Science, University of , Via De Sanctis, 86100 Campobasso, Italy; [email protected] (V.G.); [email protected] (C.G.); [email protected] (P.M.) * Correspondence: [email protected]

 Received: 25 May 2020; Accepted: 5 June 2020; Published: 9 June 2020 

Abstract: The archaeological area of Saepinum is considered the symbol of the history of Roman civilization in Molise region (Italy). It was a Samnite commercial forum and service center, then it became a Roman municipium, and, later, it was transformed into a medieval and modern rural village. Although the archaeological excavations brought to light different important public buildings, such as the theater, the forum, the basilica, different temples, and the main streets, today, there is still much to discover and study inside the well-preserved city walls. For this purpose, a ground penetrating radar (GPR) survey was realized in the space between the theater and the decumanus, allowing imaging of a complex regular pattern of archaeological features belonging to thermal buildings still buried in the soil.

Keywords: GPR; archaeological prospections; Saepinum; thermae

1. Introduction

The archaeological area of Saepinum (41◦25056.9300 N, 14◦37003.4000 E) is a plain center located at the base of the Mountain that faces the Tammaro valley, in Molise Region in the northern zone of [1] (Figure1a). The Roman city was preceded by a fortified center from the Samnite era (about 4th century B.C.) called Terravecchia di , which was conquered in 293 B.C. [2] during the third Samnite war [3,4]. Following this event, the center was abandoned and the population settled downstream at the intersection of two road axes, one at the bottom of the valley (today the Pescasseroli-Candela “tratturo”, a transhumance route); the other, perpendicular to the latter, descends from the Matese and continues towards the hills of the Tammaro valley [5]. Consequently, the new center of Saepinum was built and the two road axes were incorporated in the city, becoming the decumanus (NW-SE main road) and the cardo (NNE-SSW main road) (Figure1b,c). The Roman city, which occupies an area of about 12 hectares, is delimited by city walls whose construction was realized in the period 2 B.C.–4 A.D. [6,7] (n. 2443). The circuit, which extends for a length of about 1270 m, was equipped with 19 circular towers (currently visible), arranged at a regular distance of about 25–30 m and four doors designed as triumphal arches, with a single vault. The doors were called Tammaro Gate (NNE side, in front of the Tammaro river’s plain), Bovianum Gate (NW side, towards the city of ), Beneventum Gate (SSW side, in the direction of the city of ), and Terravecchia Gate (SSW side, towards the Matese Mountain) [8] (Figure1b).

Geosciences 2020, 10, 225; doi:10.3390/geosciences10060225 www.mdpi.com/journal/geosciences Geosciences 2020, 10, 225 2 of 14 Geosciences 2020, 10, x FOR PEER REVIEW 2 of 14

TM FigureFigure 1. 1.Location Location of of Sepino Sepino onon aa GoogleGoogle Earth™ satellite image image of of Italy Italy (a (a),), map map of of the the archaeological archaeological areaarea of of Saepinum Saepinum with with an an indication indication of of walls, walls, main main buildings, buildings, gates, gates, and and roads roads (b ()b and) and a picturea picture of of the decumanusthe decumanus flanked flanked by private by private houses inhouses a view in from a view Bovaianum from Bovaianum Gate in the Gate direction in the of direction Beneventum of GateBeneventum (c). Gate (c).

ArchaeologicalArchaeological excavations excavations that began began in in the the 1950s 1950s ha haveve brought brought to light to light only only a small a small part of part the of theRoman Roman city. city. The The archaeological archaeological analysis analysis of the of excavated the excavated and elevated and elevated structures structures has highlighted has highlighted that thatthe the period period of greatest of greatest splendor splendor for Saepinum for Saepinum was the wasAugustan the Augustan age, when age, the city when took the on citysignificant took on significanturban grow urbanth due growth to the construction due to the of construction the most important of the mostbuildings important [9]. In detail, buildings the monumental [9]. In detail, structures actually found include (Figure 1b): The theater (1 in Figure 1b, Figure 2a) and the the monumental structures actually found include (Figure1b): The theater (1 in Figure1b, Figure2a) gymnasium-porticus complex (2 and 3 in Figure 1b) located in the northern sector of the city dated and the gymnasium-porticus complex (2 and 3 in Figure1b) located in the northern sector of the city to the first half of the 1st century A.D.; the basilica located near the forensic area, built in the 1st dated to the first half of the 1st century A.D.; the basilica located near the forensic area, built in the 1st century B.C. (8 in Figure 1b, Figure 2b); the macellum [10–12], the building used as a market, dated century B.C. (8 in Figure1b, Figure2b); the macellum [ 10–12], the building used as a market, dated to to the 1st century. A.D. [7, n. 2475] (8 in Figure 1b); the cult buildings belonging to the 1st century the 1st century. A.D. [7] (n. 2475) (8 in Figure1b); the cult buildings belonging to the 1st century A.D. A.D. and located on the decumanus, next to the macellum (7 in Figure 1b); the forum of the Augustan andage located located on at the the decumanus, crossroads between next to thethe macellum cardo and (7 the in Figuredecumanus1b); the (9 forumin Figure of the1b); Augustan the thermal age locatedcomplex at theattached crossroads to the between walls near the Bovianum cardo and Gate the decumanusdating back (9to in2nd Figure century1b); A.D. the thermal(4 in Figure complex 1b, attachedFigure 2e); to the and walls the production near Bovianum buildings Gate and dating the housing back to 2nddistrict century located A.D. along (4 in the Figure decumanus1b, Figure in the2e); andstretch the productionbetween the buildings forum and and Ben theeventum housing Gate district used since located the alongAugustan the decumanusage until the in5th the century stretch betweenA.D. (5 thein Figure forum 1b, andc and Beneventum Figure 2c). Gate used since the Augustan age until the 5th century A.D. (5 in Figure1Outsideb,c and the Figure wall2c). circuit there are two necropolises, one near Bovianum Gate dated to the 1st centuryOutside A.D. the and wall the circuitother of there the Augustan are two necropolises,age located outside one near Bene Bovianumventum Gate Gate [13] dated (10 in to Figure the 1st century1b). Near A.D. the and latter the necropolis, other of the archaeological Augustan age excavations located outside brought Beneventum to light the Gate remains [13] (10 of a in medieval Figure1b). Nearsettlement the latter dated necropolis, to the 14th archaeological century. excavations brought to light the remains of a medieval settlementIn the dated 5th toand the 6th 14th centuries century. A.D., the city was the diocesan office [14] but immediately lost importanceIn the 5th due and to 6ththe growing centuries influence A.D., the of citythe near was city the diocesanof Bojano, oinffi thece [9th14] century. but immediately Most of the lost importancepopulation due of Saepinum to the growing moved influence to a hill called of the Castellum near city Sepini of Bojano, [15], inwhich the 9thlater century. took the Most name of of the populationthe actual ofSepino. Saepinum The name moved of to Sepino a hill calledappears Castellum in documents Sepini starting [15], which from laterthe 12th took century, the name but of in the actualthat period, Sepino. the The city name lost ofits Sepinogreatness appears and it was in documents reduced to startinga small village. from the 12th century, but in that period,The the interestcity lost in its the greatness archaeological and it was history reduced of Saepinum, to a small village.as happened throughout the Molise territory,The interest began in the mid archaeological-1800s. As evidenced history of by Saepinum, the rich current as happened literature, throughout many studies the Molisewere territory,carried beganout up in to the now mid-1800s. [8,16–26]. As However, evidenced archaeological by the rich current excavations literature, concerned many studies only 10% were of carried the areas inside the walls.

Geosciences 2020, 10, 225 3 of 14 out up to now [8,16–26]. However, archaeological excavations concerned only 10% of the areas inside theGeosciences walls. 2020, 10, x FOR PEER REVIEW 3 of 14 The real need to increase the knowledge of the site, the impossibility of planning extensive excavationsThe real due need to the to large increase financial the knowledge resources ofrequired, the site, and the the impossibility subsequent of management planning extensive for the conservationexcavations of due the to excavated the large structuresfinancial resources have led required, to planning and preventivethe subsequent non-invasive management geophysical for the prospectionsconservation in of order the excavated to provide, structures in a fast have way led on to vast planning areas, preventive an image non of archaeological-invasive geophysical features stillprospections buried in the in order soil. Into provide, this frame, in a difastfferent way on methods, vast areas, such an image as electrical of archaeological resistivity features tomography, still theburied magnetic in the method, soil. In the this induced frame, electromagnetic different methods, technique, such as electrical and ground resistivity penetrating tomography, radar (GPR), the magnetic method, the induced electromagnetic technique, and ground penetrating radar (GPR), are are often employed with successful results [27–48]. often employed with successful results [27–48]. In this work, the GPR technique was chosen for the survey because of the non-destructive features In this work, the GPR technique was chosen for the survey because of the non-destructive of the application, the high speed of data acquisition, and the optimal resolution of results. The main features of the application, the high speed of data acquisition, and the optimal resolution of results. objective of the application was the production of a new detailed map of buried archaeological The main objective of the application was the production of a new detailed map of buried structuresarchaeological in an unexplored structures in area an locatedunexplored between area thelocated theater between and the the decumanus theater and in the the decumanus eastern part in of thethe northern eastern thermae part of (in the yellow northern in Figure thermae1b). (in The yellow gathered in Figure information, 1b). The nonexistent gathered so information, far, will be usefulnonexistent to plan the so following far, will be actions useful of to archaeological plan the following investigation, actions ofconservation archaeological and investigation,valorization of theconservation area. and valorization of the area.

Figure 2. Pictures of the archaeological area of Saepinum: the theater (a), the basilica (b), the private Figure 2. Pictures of the archaeological area of Saepinum: the theater (a), the basilica (b), the private houses (c) near Bovianum Gate (d), and the northeastern thermae (e). houses (c) near Bovianum Gate (d), and the northeastern thermae (e).

2. Methods,2. Methods, Data Data Acquisition, Acquisition and, and Processing Processing. GPRGPR is basedis based on on the the di diffusionffusion of of electromagnetic electromagnetic pulsespulses into the soil soil and and the the recording recording of of those those re-radiatedre-radiated by buried by buried targets, targets, characterized characterized by su ffi bycient sufficient dimensions dimensions and by electromagnetic and by electromagnetic properties properties different from those of the receding ground. The quantities that are measured are the time different from those of the receding ground. The quantities that are measured are the time required for required for the wave to travel the path from the transmitting antenna to a discontinuity and return the wave to travel the path from the transmitting antenna to a discontinuity and return to the surface to the surface (double time or two way time) and the amplitude of the reflected wave. The double (double time or two way time) and the amplitude of the reflected wave. The double travel time depends travel time depends on the speed with which the wave propagates within the material and provides on the speed with which the wave propagates within the material and provides information on the information on the depth at which the reflectors are located. The amplitude, however, which depthrepresents at which how the much reflectors energy are returns located. to The the amplitude,surface after however, reflection, which depends represents on the howinitial much energy energy of returnsthe sent to the wave, surface the quantity after reflection, that it is dependsdissipated on along the initialthe way energy, and the of thecontrast sent wave,of the electromagnetic the quantity that it isproperties dissipated of along the materials the way, that and determine the contrast the ofsurface the electromagnetic of the reflection. properties A complete of description the materials of the that determinemethod theis available surface ofin thetext reflection.books, such A as complete [49–53]. description of the method is available in textbooks, such asThe [49– factors53]. that influence the performance of the system, in terms of the detectability of existing targets,The factors are the that electromagnetic influence the properties performance of the of thepropagation system,in medium terms of, which the detectability determine the of existingdepth targets,of investigation are the electromagnetic that can be reached, properties which of therefore the propagation varies from medium, point to which point. determine Since the attenuation the depth of investigationof the means that is cana function be reached, of the which radiated therefore frequency, varies the from use pointof low to-frequency point. Since antennas the attenuation generally of allows extension of the penetration depth of the signals; however, this is at the expense of the resolution.

Geosciences 2020, 10, 225 4 of 14 the means is a function of the radiated frequency, the use of low-frequency antennas generally allows extension of the penetration depth of the signals; however, this is at the expense of the resolution. In this case, the RIS K2 Georadar (IDS GeoRadar s.r.l., Pisa, Italy), equipped with a multi-frequency TRMF (Time-Reversal Matched Filter) antenna (600–200 MHz), was used during data acquisition Geosciences 2020, 10, x FOR PEER REVIEW 4 of 14 (Figure3b). An area of about 10,700 m 2 was investigated through 342 profiles, NE-SW oriented, distributedIn on this two case, bands the RIS overlapping K2 Georadar (IDS by GeoRadar 1.5 m (Figure s.r.l., Pisa,3a). Italy), In practice, equipped the with two a multi acquisition-frequency bands were dividedTRMF (Time into- sub-cellsReversal Matched with a maximum Filter) antenna width (600 of–200 20 m MHz), and a was length used of during 27 m data(western acquisition band) and 36 m (eastern(Figure 3b)band).. An The arealocation of aboutof 10,700 cell intersectionsm2 was investigated was accurately through 342measured profiles, through NE-SW aoriented, total station using georeferenceddistributed on two fiduciary bands overlap pointsping for by the 1.5 absolute m (Figure position. 3a). In practice, Profiles the were two acquisition spaced 0.5 bands m considering were the totaldivided size ofinto the sub investigation-cells with a maximum area and width the of investigative 20 m and a length purposes, of 27 m so (western as to achieve band) and the 36 detailed m (eastern band). The location of cell intersections was accurately measured through a total station using resolution most useful for data processing and their interpretation. Traverses were collected using a georeferenced fiduciary points for the absolute position. Profiles were spaced 0.5 m considering the zig-zagtotal collection size of the mode investigation in order area to and halve the investigative the acquisition purposes, times. so as Data to achieve acquisition the detailed was resolution carried out in five daysmost during useful the for morning data processing trying and to work their in interpretatio the samen. soil Traverses moisture were conditions collected in using order a zig to- avoidzag an amplitudecollection offset. mode Nevertheless, in order to halve a variation the acquisition over suchtimes. aData large acquisition period consideringwas carried out the in broadfive days dataset is inevitable.during the morning trying to work in the same soil moisture conditions in order to avoid an amplitude Radaroffset. reflectionsNevertheless, ona variation each line over weresuch a recordedlarge period as considering 16-bit data the broad in a dataset time windowis inevitable. of 90 ns, acquiring 512Radar samples reflections per on radar each scan line were at 25 recorded scans per as mark16-bit data (unit in/marker, a time window 1). of 90 ns, acquiring 512 samples per radar scan at 25 scans per mark (unit/marker, 1).

Figure 3. Grid data acquisition on a Google EarthTM satellite image (a) and the RIS K2 Georadar during Figure 3. Grid data acquisition on a Google Earth™ satellite image (a) and the RIS K2 Georadar during the survey (b). the survey (b). Raw data were processed using the IdsGred [54] and GPR−SLICE 7.0 software [55] using Raw data were processed using the IdsGred [54] and GPR SLICE 7.0 software [55] using standard standard methodological approaches: Data and trace editing, −subtraction of the dc-drift (wobble) in methodologicalthe data, time approaches:-zero correction Data matched and trace considering editing, the subtraction starting point of theof the dc-drift wave (22) (wobble) and the incenter the data, time-zerofrequency correction of 612 matched MHz, bandpass considering filter (low thestarting cutoff: 63 point MHz; of upper the wave cutoff: (22) 1252 and MHz) the, centerbackground frequency of 612remo MHz,val bandpass (the length filter of the (low filter cuto wasff : set 63 to MHz; 1000 ensuring upper cuto thatff the: 1252 same MHz), average background scan across removalthe (the lengthradargram of the is filtersubtracted was setfrom to every 1000 of ensuring the 512 scans that as the suggested same average in [55]), scanand automatic across the gain. radargram is subtractedFinally, from every the whole of the data 512 scans set was as usedsuggested to extract in [ 55 horizontal]), and automatic slices relative gain. to different time windows equal to 4 ns with an overlap 1–2 ns. As the data set was so large and, as a consequence, the Finally, the whole data set was used to extract horizontal slices relative to different time windows dielectric constant of the soil could be extremely variable, we avoided converting time to depth using equal toa mean 4 ns withvalue anwith overlap the possibility 1–2 ns. of As obtain the dataing an set arbitrary was so and large inaccurate and, as estimate. a consequence, Nevertheless the dielectric, an constantaverage of the velocity soil could of 100 be m/mms extremely was variable,matched fitting we avoided some hyperbolas, converting that time is, the to depthexpected using buried a mean value withfeature the is possibilityvery shallow, of confined obtaining in the an volume arbitrary of soil and included inaccurate in the estimate. range 0.2– Nevertheless,1.5 m. This evaluation an average velocityis ofin agreement 100 m/mms with was the matched archaeological fitting data some considering hyperbolas, that the that excavated is, the expected structures buried in the featurearea is appeared in the soil at few decimeters from the surface.

Geosciences 2020, 10, 225 5 of 14 very shallow, confined in the volume of soil included in the range 0.2–1.5 m. This evaluation is in agreement with the archaeological data considering that the excavated structures in the area appeared in the soil at few decimeters from the surface.

3. ResultsGeosciences and 2020 Discussion, 10, x FOR PEER REVIEW 5 of 14

3.For Results brevity, and examples Discussion of eight radargrams are reported in Figures4 and5, four for each band of acquisition. Here, circles and rectangles are used for the data interpretation using a different color for For brevity, examples of eight radargrams are reported in Figures 4 and 5, four for each band of eachacquisition. radargram. Here, The circles location and ofrectangles the circles are used on the for top the ofdata the interpretation radargram using represents a different the color projection for of deepereach anomalies radargram. on The the location surface, of a the choice circles appositely on the top made of the so radargram as not to represent cover thes the section proje withction graphicof elements.deeper The anomalies images on put the in surface, evidence a choice several appositely punctual made near-surface so as not toanomalies cover the section (marked with with graphic diff erent coloredelements. circles) The that images are associated put in with evidence possible several targets punctual stretched near below-surface the anomalies surface, such (marked as foundations, with walls,different or channels, colored cut circles) diagonally that are orassociated transversely. with pos Furthermore,sible targets stretched great areas below with the sub-horizontal surface, such as lying or highlyfoundations, disturbed walls bands, or channels, is also evidence cut diagonally (indicated or transversely. with colored Furthermore, rectangles), great which areas is with related sub- to the septahorizontal of walls orlying collapsed or highly areas disturbed with bands an accumulation is also evidence of stones.(indicated All with anomalies colored arerectangles), located which in the time is related to the septa of walls or collapsed areas with an accumulation of stones. All anomalies are window of 0–30 ns. located in the time window of 0–30 ns.

FigureFigure 4. Radargrams 4. Radargrams 9, 9, 62, 62, 112, 112, andand 151 with with an an indication indication of ofthe the main main anomalies. anomalies.

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FigureFigure 5. 5.Radargrams Radargrams 223,223, 257,257, 291,291, and 330 with with an an indication indication of of the the main main anomalies. anomalies.

TheThe horizontal horizontal slices, better better than than vertical vertical sections, sections, allow allow recognition recognition of a complex of a complex system of systemregular of regularhighs highsof the ofamplitude the amplitude of the electromagnetic of the electromagnetic signals (Figure signals 6). (Figure Starting6). from Starting the fromlowest the to lowestthe highest to the highesttime interval, time interval, an interesting an interesting intertwining intertwining of linear anomalies of linear anomaliesgradually emerges, gradually which emerges, let to being which able let to beingto imagine able to the imagine presence the of presence articulated of articulatedbuildings buried buildings in the buried shallow in subsoil. the shallow It is possible subsoil. toIt recognize is possible todifferent recognize types different of alignments: types of alignments: Several parallel/perpendicular Several parallel/perpendicular to the long sideto the of long the gridside of(NW the-SE grid (NW-SEoriented oriented as the decumanus) as the decumanus) characterized characterized by high values by high of the values amplitude of the and amplitude different and diagonals different diagonalsarrangements arrangements with medium with measured medium measuredvalues, almost values, intertwined almost intertwinedwith each other. with each other. ForFor an an archaeological archaeological interpretation, interpretation, thethe most significant significant slice slice related related to to 14 14–18–18 ns ns was was taken taken into into consideration.consideration. In In Figure Figure7, a 7, contour a contour map map is shown is shown by applying by applying the logarithmic the logarithmic scale to scale better to represent better represent the data set that extends over a very wide range of values and to highlight particular trends the data set that extends over a very wide range of values and to highlight particular trends in the in the variation of the data. variation of the data. Superimposed on the map (Figure 7), the locations of the eight analyzed radargrams are shown Superimposed on the map (Figure7), the locations of the eight analyzed radargrams are shown using the same graphics (circles and rectangles with the same color assignment) used in Figures 4 using the same graphics (circles and rectangles with the same color assignment) used in Figures4 and5 and 5 for the anomalies’ interpretation. In this way, it is clear to understand how the colored point foranomalies the anomalies’ mentioned interpretation. above are In walls this way, intercepted it is clear transversely to understand and how the thehorizontal colored anomalies point anomalies are mentionedwalls/collapses above scanned are walls along intercepted their entire transversely length directly and thefrom horizontal the top surface. anomalies are walls/collapses scannedThe along same their map entire was correctly length directly georeferenced from the and top positioned surface. on a Google EarthTM image, as shown in The Figure same 8. Here,map was it is correctly possible georeferenced to note that the and supposed positioned alignments on a Google are in Earth accordance™ image, with asshown the inthermal Figure8 system. Here, partially it is possible excavated to note to the that north the and supposed with the alignments private houses are that in accordance are located west with of the thermalthe decumanus. system partially excavated to the north and with the private houses that are located west of the decumanus.In Figure 9, an interpretation of the archaeological structures is attempted. It is possible to distinguishIn Figure at9 ,least an interpretationfour groups of anomalies of the archaeological probably corresponding structures to is as attempted. many separate It is building possibles. to distinguish at least four groups of anomalies probably corresponding to as many separate buildings.

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FigureFigure 6. 6.GPR GPR timetime slicesslices in the range range 9 9–27–27 ns ns (distances (distances inin meters). meters).

AA first first group, group, interpreted interpreted withwith magentamagenta lines, represents represents the the probable probable closure closure of ofthe the thermal thermal complexcomplex that that is is located located north of of a awall wall partition partition about about 28 m 28 long. m long. It is bordered It is bordered to the south to the by south a semi by- a circular structure with a diameter of about 12 m in the center (1 in Figure 9) and two rooms (4 × 4 m) semi-circular structure with a diameter of about 12 m in the center (1 in Figure9) and two rooms at the sides. (4 m 4 m) at the sides. × Moving to south, a second articulated building (marked with green lines) is hypothesized. The Moving to south, a second articulated building (marked with green lines) is hypothesized. overall size of the anomalies is about 24 × 56 m. In particular, a structure is supposed that is The overall size of the anomalies is about 24 m 56 m. In particular, a structure is supposed that is symmetrical with respect to the NE-SW-oriented× center, characterized by two specular semicircles symmetrical(diameter of with 12 mrespect similar to to the the NE-SW-oriented previous one, 2 center, and 3 in characterized Figure 9). In by the two center, specular on the semicircles line of (diametersymmetry, of 12 there m similar is a square to the anomaly previous (4 one,in Figure 2 and 9) 3 flanked in Figure on9 the). In sides the center,by two onrooms the line10 m of long symmetry, and there4 m is wide a square (5 and anomaly 6 in Figure (4 in9). Figure On the9 )southern flanked side, on the an sidesalignment by two 30 roomsm long, 10 bordered m long by and two 4 mcells wide (5 andof equal 6 in Figuresize (4 9×). 4 Onm) at the the southern ends (7 side,and 8 anin alignmentFigure 9), closes 30 m long,the complex. bordered by two cells of equal size (4 m 4 m) at the ends (7 and 8 in Figure9), closes the complex. × Geosciences 2020, 10, 225 8 of 14

Geosciences 2020, 10, x FOR PEER REVIEW 8 of 14 The third anomaly is located in front of the temple, which is located west of the decumanus and The third anomaly is located in front of the temple, which is located west of the decumanus and has dimensions of 26 m 14 m (indicated in blue, 9 in Figure9). Inside, it is possible to recognize has dimensions of 26 × × 14 m (indicated in blue, 9 in Figure 9). Inside, it is possible to recognize orthogonal divisions between them. orthogonal divisions between them. The fourth group has considerable dimensions of 70 m 22 m (in red in Figure9). The complex is The fourth group has considerable dimensions of 70 × ×22 m (in red in Figure 9). The complex is symmetrical with respect to the NE-SW-oriented center and several regular patterns can be identified. symmetrical with respect to the NE-SW-oriented center and several regular patterns can be identified. From north to south, the following features are highlighted: From north to south, the following features are highlighted: Three cells (10 in Figure9) flanked by two single alignments that close orthogonally with two septa; • Three cells (10 in Figure 9) flanked by two single alignments that close orthogonally with two Asepta; 10 m 10 m square anomaly (11 in Figure9); • ×  FiveA 10 cells × 10 of m which square the anomaly central (11 one in is Figure slightly 9); larger and bordered to the north from an open room •  (12Five in cells Figure of9 which); the central one is slightly larger and bordered to the north from an open room Regular(12 in Figure and symmetrical 9); segments (13 in Figure9); •  ARegular complex and with symmetrical articulated segments internal (13 divisions in Figure bordered 9); by two large lateral rooms (14 and 15 in •  FigureA complex9); and with articulated internal divisions bordered by two large lateral rooms (14 and 15 in Figure 9); and A semicircular anomaly of similar dimensions to the previous discussed (16 in Figure9). • A semicircular anomaly of similar dimensions to the previous discussed (16 in Figure 9). In addition, analyzing the completely horizontal slices, oblique anomalies are interpreted In addition, analyzing the completely horizontal slices, oblique anomalies are interpreted (Figure 10). They are regularly distributed, in some cases symmetrical, and often connect anomalies, (Figure 10). They are regularly distributed, in some cases symmetrical, and often connect anomalies, withwith di differentfferent orientations orientations just just discussed discussed inin thethe corners.corners.

FigureFigure 7. 7.Time Time slice slice relative relative to 14–18 to 14 ns–18 with ns the with location the location and the and interpretation the interpretation of the eight of radargrams the eight reportedradargrams in Figures reported4 and in 5Figures (distances 4 and in 5 meters). (distances in meters).

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TM FigureFigure 8. 8.Time Time slice slice relative relative to to 14–1814–18 nsns overlappedoverlapped to a Google Earth EarthTM™ satellitesatellite image.image. image.

TM Figure 9. Interpretation lines reported on a Google Earth TM satellite image. FigureFigure 9. 9.Interpretation Interpretation lineslines reportedreported onon a Google Earth Earth™ satellitesatellite image. image.

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FigureFigure 10. 10.Oblique Oblique anomaliesanomalies on selected time slices slices ( (aa)) and and interpretation interpretation lines lines reported reported on on a aGoogle Google TM EarthEarth™ satellite satellite image image ((bb).).

4.4. Conclusions Conclusions TheThe GPR GPR investigations investigation conducteds conducted in the in ancient the ancient city of Saepinum city of Saepinum provided importantprovided informationimportant aboutinformation the imaging about ofthe archaeological imaging of archaeological structures still structures buried in still the buried subsoil. in the subsoil. GivenGiven the the articulation articulation ofof thethe anomalies and their their geometric geometric characteristics characteristics enriched enriched with with apsidal apsidal environments,environments, it it can can be be assumed assumed that that they they belong belong to ato thermal a thermal complex. complex. This This allowed allow used to us fully to fully define thisdefin typee this of construction,type of construction, which waswhich partially was partially excavated excavated in this in sector this sector to date. to date. ParticularlyParticularly clear clear are are the the contours contours of of the the four four identified identified buildings buildings or or building building complexes. complexes. The The first representsfirst represents the closure the closure of what of what is visible is visible today today in in the the thermae; thermae; thethe second,second, with with the the two two apsed apsed roomsrooms and and thethe various environments environments identified, identified, represents represents a novelty a novelty in the in knowledge the knowledge of the of site the; the site; thethird, third, of dubious of dubious function, function, has hasvery very regular regular features features;; and the and fourth, the fourth, of imposing of imposing size, has size, the has clear the constructive characteristics of the thermae. The latter, similar to the known thermae (for example, clear constructive characteristics of the thermae. The latter, similar to the known thermae (for example, those of Domu’e Cubas, Sardinia, Italy), could be composed from south to north by a changing room those of Domu’e Cubas, Sardinia, Italy), could be composed from south to north by a changing room (apodyterium), a cold environment (frigidarium), a warm environment (tepidarium), a warm room (apodyterium), a cold environment (frigidarium), a warm environment (tepidarium), a warm room (calidarium), and a laconicum (room with hot air) with praefurnium (oven) and suspensurae. (calidarium), and a laconicum (room with hot air) with praefurnium (oven) and suspensurae. In this context, the numerous oblique anomalies intercepted are justified and thus can be In this context, the numerous oblique anomalies intercepted are justified and thus can be interpreted interpreted as small channels for the supply of water to the various rooms. as small channels for the supply of water to the various rooms. The results presented, in addition to enriching the knowledge of the site by increasing the The results presented, in addition to enriching the knowledge of the site by increasing the percentage of surface studied so far, have contributed to confirming the great wealth that the city had percentageuntil the 4th of surfacecentury studied A.D. [8] so (Figurefar, have 11). contributed Furthermore to confirming, it can be the con greatsidered wealth a valid that and the city useful had untilexample the 4th of century geophysical A.D. [8 investigations] (Figure 11). Furthermore, for archeology it can available be considered to scientists a valid and and local/national useful example ofdecision geophysical makers investigations that operate in for the archeology frame of cultural available heritage to scientists protection and localfor planning/national future decision activities makers. that operate in the frame of cultural heritage protection for planning future activities.

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Figure 11. Uploaded archaeological map of the ancient Saepinum with the addition of the time slice Figure 11. Uploaded archaeological map of the ancient Saepinum with the addition of the time slice relative to 14–18 ns. relative to 14–18 ns.

AsAs the the results results look look to to be be so so promising, promising, futurefuture fieldfield campaignscampaigns of prospection prospection are are planned planned using using the area as a test site, where the following parameters of acquisition will be varied: The frequency of the area as a test site, where the following parameters of acquisition will be varied: The frequency the antennas and the spacing between profiles with a minor interline, as well as integrating the GPR of the antennas and the spacing between profiles with a minor interline, as well as integrating the measurements with magnetometry, resistivity tomography, and induce electromagnetic methods. GPR measurements with magnetometry, resistivity tomography, and induce electromagnetic methods. The aim is to define the limits and advantages and to set a protocol of best settings for each method The aim is to define the limits and advantages and to set a protocol of best settings for each method when studying a real case. Anyway, the research is still ongoing, and the project regards the when studying a real case. Anyway, the research is still ongoing, and the project regards the prospection prospection of all free areas inside the city walls. of all free areas inside the city walls. Author Contributions: Conceptualization, M.C. and P.M.; methodology, M.C. and P.M.; validation M.C. and AuthorP.M.; formal Contributions: analysis, Conceptualization,M.C. and P.M.; investigation, M.C. and M.C., P.M.; V.G. methodology, and C.G.; M.C.data curation, and P.M.; M.C., validation V.G. and M.C. P.M and.; P.M.;writing formal—original analysis, draft M.C. preparation, and P.M.; investigation,M.C., V.G. and M.C., P.M. V.G.; writing and C.G.;—review data and curation, editing, M.C., M.C V.G.. and and P.M. P.M.;; writing—originalsupervision, M.C draft. and preparation, P.M.; project M.C., administration, V.G. and P.M.; M.C writing—review. and P.M. All andauthors editing, have M.C. read and and P.M.; agreed supervision, to the M.C. and P.M.; project administration, M.C. and P.M. All authors have read and agreed to the published version of published version of the manuscript. the manuscript. Funding:Funding:This This research research received received no no external external fundingfunding Acknowledgments:Acknowledgments:This This research research was carried was carried out with out the with authorization the authorization of the Superintendence of the Superintendence for Archaeological for Heritage,Archaeological Regional Heritage, Directorate Regional for Cultural Directorate and Landscape for Cultural Heritage and Landscape of Molise (Ministry Heritage for of CulturalMolise (Ministry Heritage for and ActivitiesCultural andHeritage for Tourism) and Activities as part and of afor research Tourism) program as part aimedof a resear at definingch program a geophysical aimed at defining investigation a geophysical protocol forinvestigation cultural heritage protocol promoted for cultural by the heritage University promoted of Molise by the (MBAC-SBA-MOL, University of Molise U_PROT (MBAC 0001573,-SBA-MOL, 04/04 U_PROT/2014). Conflicts0001573, of 04/04/2014). Interest: The authors declare no conflict of interest. Conflicts of Interest: The authors declare no conflict of interest.

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