London and Middlesex Archaeological Society Transactions, 67 (2016), 99—131 THE MEDIEVAL CITY DITCH AT BISHOPSGATE, HERON TOWER, LONDON EC3 David Sorapure With contributions by Ian M Betts, Lyn Blackmore, Lynne Keys, Alan Pipe, Natasha Powers, Beth Richardson, Rob Scaife, Amy Thorp and Virgil Yendell SUMMARY INTRODUCTION In 2007 excavations in advance of the construction In the autumn of 2007 in advance of the of Heron Tower revealed a number of scattered Roman construction of Heron Tower, Museum of pits. The excavations were situated in the area just London Archaeology (MOLA) undertook beyond London’s former Roman and medieval city archaeological excavations at the property wall, adjacent and to the east of Bishopsgate. Current formerly known as Kempson House, 25—37 projections of the line of the Roman city wall suggest Camomile Street and Bishops House, 106— that it ran north-west to south-east across the southern 126 Bishopsgate, London EC3 (NGR 533250 edge of the site. No traces of the Roman defences were 181450, site code KPH05). The site is bounded discovered; any trace of the city wall and its associated by Houndsditch to the north, Bishopsgate ditch were apparently removed by the extreme truncation to the west, Outwich Street to the east and caused by the construction of the modern basements. Camomile Street to the south (Fig 1). Earlier The main feature of archaeological interest on site fieldwork conducted in 2000 (CMI00) and was a significant cross section of the truncated medie- 2005 (KPH05) revealed negative evidence for val city ditch. Two trenches were excavated across the the presence of the Roman city wall. line of the city ditch. Fieldwork revealed that the ditch The excavation consisted of two trenches was 17—20m wide and aligned east to west. Sections (Fig 2). Trench 1 was located in the basement cut through the infilled ditch revealed that some of its of Kempson House and Trench 2 in the lower fills were waterlogged and possibly waterlain. basement of Bishops House, built in 1960 Within the upper fills there were frequent episodes of and 1976 respectively. Due to the extensive recutting and clearing, whilst medieval pottery and modern truncation and the basements of the environmental analysis revealed deposition sequences two buildings, the top of the truncated natural of refuse, rich in organic material, interspersed with deposits lay at c.11.02m OD in Trench 1 and periods of relatively sterile deposition. 11.16m OD in Trench 2, whilst ground level The earliest phase of this ditch dates to the mid-11th adjacent to the site was approximately 15.4m to later 12th century. The initial infilling of the ditch OD. The medieval city ditch was identified in began slowly, then it gradually increased after a major both trenches, 17—20m wide, running west recutting event in the early 13th century, to reach a to east across the site. Deposit survival over peak during the 14th to 15th centuries. From the late much of the site was compromised by modern 15th century to the mid-17th century the city ditch in concrete ground beams and the 19th-century this area underwent a fairly rapid process of infilling Irongate sewer, which ran west—east across the as it fell out of use. Over time its width was progressive- site, through Trench 1 and running just south ly reduced by successive recutting events. of Trench 2 (Fig 2). This resulted in the 99 100 David Sorapure the form of a single, continuous open trench and was modified to take the form of an open trench to the north with a series of bays (Areas A, B, C and D) and smaller slots to the south (Slot 1, Slot 2 — which was abandoned due to truncation — and Slot 3, Fig 2). Despite the modern intrusions, the width of the medieval city ditch was exposed in Trench 1. The ditch fills were excavated and recorded in section (see Figs 6 and 7), east facing in Trench 1 and west facing in Trench 2. After the section had been recorded each distinct deposit, or context, was removed and pottery and other finds recovered. The site archive will be deposited under the site code KPH05 in the Museum of London’s Archaeological Archive,1 Mortimer Wheeler House, 46 Eagle Wharf Road, London N1 7ED, where it may be consulted by prior arrangement. The analysis of the excavation resulted in a series of specialist research archives which will be deposited as part of the archive. The results of assessed strata and all assemblages of artefacts, environmental and Fig 1. Site location (City of London scale 1:50,000, osteological remains were recorded on the site plan 1:10,000) MOLA Oracle database. This article employs standard Museum of London codes for ceramics and building materials; complete decision to excavate where possible between lists of these codes, their expansions the concrete ground beams and the Irongate and date ranges are available online.2 sewer. Trench 1 was therefore unable to take Expansions of pottery codes are given at Fig 2. Location of Trenches 1 and 2 (scale 1:1000) The Medieval City Ditch at Bishopsgate, Heron Tower, London EC3 101 the first mention in a text section. Context the modern basements of Bishops House numbers are denoted by square brackets [1] and Kempson House. and accessioned finds are shown in angled brackets <1>. Certain categories of finds have Roman Period Background been given illustration numbers preceded by a letter denoting their category, for The site of Heron Tower lies outside and example pottery, <P1>. The context details adjacent to part of the Roman city wall, concerning the illustrated finds are given in which was constructed during c.AD 180—225 the figure captions. Land-use entities consist (Maloney 1983; Sankey & Stephenson 1991; of Open Areas (OA) and Structures (S). Fig 3). The landward portion of the Roman Site codes referenced in this article relate to city wall was just over 2 miles (3.2km) in length MOLA investigations. with six gates and incorporated elements of an earlier fort at Cripplegate. At the site of DRIFT GEOLOGY (PERIOD 1) Heron Tower, the wall ran on a north-west to south-east alignment and the southern The drift geology consisted of compact, edge of the site lay close to the known line sandy Pleistocene, Thames river terrace of the Roman wall (Figs 3 and 4). This is gravel (highest point 10.66m OD), overlain confirmed by a conjectured alignment of the by brickearth, comprising a moderate to Roman wall, based on extending the wall’s compact sandy silt varying in colour from line from locations nearby where its remains orange and brown to light yellow or pinkish were observed in 1876 (see below; Price 1880, brown (highest point c.11.16m OD) (OA1, 28) and through archaeological fieldwork, not illustrated). The presence of a possible including investigations at 27—29 Camomile palaeochannel flowing in a south-westerly Street (COT88), 58—60 Houndsditch (HSD89) direction was indicated by current bedding and 63—71 St Mary Axe (BUN88). of silts and sands at the southern end of Surviving sections of the wall are protected Trench 2. These deposits probably date to as Scheduled Ancient Monuments and the the Late Devensian (c.25,000—c.11,500 BP). Scheduled Monument Constraint Area In general, the natural deposits dipped extended into the south-western corner southward lying between 9.60m and 8.82m of the site, but did not continue across the OD in Trench 1 and 9.60m to 8.67m OD in entire site (Fig 4). The reasons for this are Trench 2. No prehistoric deposits or finds uncertain but may be based on a reference were discovered at Heron Tower. to the demolition and removal of a bastion and a 18.29m-long stretch of the wall above plinth level in 1876 (RCHME 1928, 86). ROMAN ACTIVITY, c.AD 120—200 One of the Roman city wall’s six gatehouses (PERIOD 2) AND c.AD 200—400 became Bishopsgate, which was located across (PERIOD 3) what is now Bishopsgate road immediately Roman Ground Level outside the south-western corner of the site. It is probable that the Roman gatehouse at Judging by the recorded height of Roman Bishopsgate was of a similar design to the ground level from sites within the vicinity one at Newgate and consisted of a double of Heron Tower, it appears that the modern entrance flanked by rectangular guard truncation of the Roman ground surface on rooms. In 1905 part of the gatehouse was site was at least c.2m. At 58—60 Houndsditch recorded at the northern side of the junction (HSD89), 55m to the south-east of Heron of Wormwood Street and Bishopsgate Street Tower, the base of the Roman city wall (RCHME 1928, 97—8). On the outside of was discovered at c.11.95m OD and the the Roman city wall was a berm (between extramural Roman ground level at 12.26m 2.7m and 5.2m wide), beyond which was a OD. At Heron Tower the maximum height of V-shaped defensive ditch, c.4m wide and up surviving natural brickearth was at c.11.16m to 2m deep (Maloney 1983, 101). This ditch OD. Therefore, even to the south of Trench was found 170m west of the site at 90—94 Old 1, no evidence for the Roman city wall is Broad Street and 63—64 New Broad Street likely to have survived the construction of (BRO90). An east—west Roman ditch, about 102 David Sorapure Fig 3. Location of the site in relation to Roman London.