A watching brief was undertaken by Colchester Archaeological Trust at 3-7 Museum Street in 2010, during refurbishment. This involved the contractors hand-digging a number of trenches (T1-T6) to take concrete foundations for posts, ground beams and other structural supports. They also lowered, in places, the level of the deposits under the modern floors. T1 was 3.4m deep and was shored; T2-T4 were excavated to a depth of 1.5m; T5 was 1.7m deep and T6 was 1.9m deep. The trenches and the stripping were monitored by CAT during intermittent site visits. <1> During the watching brief, a trench (T1) on the street frontage was dug to a depth of 3.4 m. The lower 2m of the trench consisted of a dark greyish-brown fill (F2; Sx 2) containing Roman building materials such as fragments of brick, tile, mortar, opus signinum, septaria and to a lesser extent greensand, as well as a quantity of stone fragments with a laminated ‘flaggy’ appearance. There were also three fragments of marble and one of worked stone. Due to the presence of shoring, it was not possible to examine this deposit in detail, although it was probably the backfill of a large post-Roman robber trench. The upper 0.6m or so of the fill (L6), in particular, contained large quantitiesof mortar and brick/tile fragments. Natural sand (L8) was probably reached in part of the trench at a depth of 3.4m, although elsewhere in the trench F2 extended below this depth. If this was a robber trench, rather than a post-Roman ditch, it was probably for a large Roman foundation, only 5m to the north of the south precinct wall. No significant dating evidence was recovered from F2, although it was sealed by a medieval foundation. A thick layer of dump/makeup (L9) was observed in the bottom of both T5 and T6. This was a mixed yellowish-brown loamy sand with moderate gravels. It was at least 0.8 m thick and lay roughly 1.0-1.8 m below the level of the modern floor (L1). It contained sparse fragments of stone, Roman brick/tile, mortar and oyster shell, but no good dating evidence. It was sealed by dark greyish-brown, post-Roman topsoil or ‘dark earth’ (L4), the lower part of which was rather rubbly. The sandy layer L9 perhaps formed part of the Norman inner bailey rampart. A similar-looking deposit (L5) was observed in the eastern part of T1, although here it was only approximately 0.25m thick (roughly 1.2-1.45m below the internal floor-level). It sealed the probable robber trench (F2), and was sealed by post-Roman topsoil (L4) and the medieval foundation for the south gate (F1). This layer may also be associated with the construction of the inner bailey defences. During the excavation of T6 under the doorway in the north-east corner of 3-7 Museum Street in 2010, some human bone was recovered by the contractors. This came from below the modern brick foundation at a depth of between 1.0m and 1.9m below the modern floor level. A brief search in the bottom of the trench did not reveal any evidence of a grave cut or of further human bone. The bone consisted mainly of lower limb bones from a single adult individual, including fragments of pelvis, femur, tibia and fibula. There were also some feet and finger bones, the sacrum, several lower vertebrae and pieces of rib bone, and fragments of radius and ulna. The bone was probably from a burial of 16th- or 17th century date. During this time the castle bailey was used for the burial of prisoners housed in the keep (Drury 1983, 406-7). <2> Most of these burials were aligned east to west, although other alignments were also recorded, and there was no trace of coffins. The human bone found in 2010 was re-buried on site. A small rectangular brick cellar (F6) was partially uncovered by the contractors during the lowering of the level of the deposits under the modern floor at the rear of 3-7 Museum Street in 2010. The cellar had a barrel-vaulted roof and measured approximately 4m north-south by 2.75m east-west externally. Further evidence for the extensive foundations defined in 1986 was uncovered during the watching brief at 3-7 Museum Street in 2010. <1>