Archaeological work - mainly watching briefs with selected excavation - was carried out between April 2005 and February 2006 in advance of the construction of the new mid site building (Area B) and in advance of the construction of an access road on its east and north sides (Area A, totaling 740m²). Pipe trenches for run-off water down-slope were also monitored in Area A. Services required the Roman town wall to be breached to allow a pipe to pass through it. In advance of this work, and to provide access for the contractors, a deep vertical shaft was archaeologically excavated against the inner face of the town wall from modern ground-level to below the base of the wall (Area C). <1> In Insula 1a, there was a large building consisting of surviving in situ masonry wall foundations, robbed-out wall lines, and of tessellated, opus signinum and mosaic floors (CAT Building 21, MCC2970). Associated finds, principally marble and decorated wall-plaster, indicate that this was a high-status building. To the north of CAT Building 21 (MCC2970), also in Insula 1a, a separate structure with a timber water channel (CAT Building 212, MCC2969) may have been a room of a bath-house associated with CAT Building 21, or possibly a shrine to a water deity. In Insula 1b, to the east of CAT Building 21 (MCC2970) and CAT Building 212 (MCC2969) and across the previously unknown gravel street dividing Insula 1a from Insula 1b, there was the southwest corner of another possibly high-status building, with decorated wall plaster, surviving in situ masonry wall foundations and opus signinum floors (CAT Building 214, MCC2968). The assemblage of decorated wall-plaster from a pit (MCC2971), adjacent to CAT Building 214 (MCC2968), is important, being painted in imitation of marbles and opus sectile. The excavation of the shaft against the inner face of the Roman town wall went through the Roman rampart and revealed the construction road below. It also exposed 6.84 m of standing Roman masonry, 3.3 m of which was faced with alternating bands of septaria and Roman brick. Parapet walk level can be inferred at approximately 6.70 m above Roman street level. Significant information regarding the town wall rampart was also discovered from this trench, along with information regarding an earlier construction road which appears to have extended around the inside of the town wall. This was positioned around two meters away from the wall and its existence suggests that when the wall was originally constructed, it was a free-standing structure with no internal rampart. This may have been a construction road for the town wall. This road went out of use after a few years and a rampart consisting of a succession of layers was built up to strengthen the wall. Dating evidence from the town demolition debris used to built this rampart dates it to about the mid second century. Also on the inner face of the Roman town wall, there was a substantial piece of robbed masonry exposed in a pipe trench which is best interpreted as the remains of a previously unknown interval tower. There appears to have been very little post-Roman activity on the land now occupied by the Sixth Form College. Recent excavation and evaluation work has shown that a substantial depth of topsoil accumulated over the site in this period. The usual interpretation of this soil accumulation, often found in Colchester, is that the land was left open and/or was used for small-scale agriculture or horticulture in the Anglo-Saxon and medieval periods. <1>