The precinct wall of St John's Abbey, only fragments of the original wall survive. However, most of the original course is known.

About 140m of surviving abbey wall was destroyed in 1972 as part of the work for St Botolph's roundabout. The wall stood to a height of about 2.75m and tapered in width from about 1.0m at the base to 0.6m at the top. Once 16th century brick and stone refacing had been removed an older wall was revealed, the original structure was built entirely of reused Roman building materials and the original face contained many put-log holes. A dump of soil thought to relate to the fire of 1133 sat against the base of the wall suggesting the wall could be an original feature of the abbey, laid out in 1095. The absence of peg tile suggests that the wall must be pre late 13th century. The refacing of the wall is likely to have been the work of the Lucas family who took over the precinct soon after the dissolution.<1>

At St Giles Church, the line of the precinct wall appears to have been moved southwards during the Lucas family period (late 16th century-1648); this was to enable parishioners to access the church from the north without having to pass through the precinct grounds.<2>

The precinct wall is shown on Speeds map of 1610.<3>

In 1972, the north-east corner of the precinct was lowered by machine for a new roundabout and as a result the inside of the precinct wall was exposed and recorded during a watching brief. For much of its length the inner face was well preserved and revealed put-log holes.<4> About 140m of the surviving abbey wall was destroyed. The wall stood to a height of about 2.75m. The wall may have predated the 13th century.<5>

The southern face of the abbey precinct wall foundation was exposed in Trench 26 of the evaluation in 2007. It was solidly built with Roman brick and tile, septaria chunks and greensand fragments bonded in a yellow sandy lime mortar.<6>

Further investigation of the Abbey precinct wall occurred during the redevelopment of Area B1b (previously known as Flagstaff House, now known as Arena Place) in 2015-17 (see ECC2911, ECC2912 and ECC2913). Approximately 16.5m of surviving in situ foundation from the precinct wall was revealed in excavation Area A and during monitoring around Block A, constituting part of the southern east/west wall. The foundation was 0.8m wide and was made of septaria, greensand stone and reused Roman ceramic building material set into a lime-mortar, similar to that seen in 1972 when part of the standing wall was demolished (CAR 9, 219). Between Area A and Block A, a short stretch (c.9m) of precinct wall survives built into the southern wall of Block F (a garrison wagon shed dated to the late 19th century). In 2016, as part of the current redevelopment, the wall was surveyed and conserved.<7>

A programme of Level 3 recording was carried out by Colchester Archaeological Trust following the collapse of a section of the west precinct wall along Flagstaff Road in 2018.<8>