A watching brief was carried out by Colchester Archaeological Trust during the excavation of foundation trenches and a drainage trench, forming part of a new extension to an existing garage (to form a new dwelling). Little archaeological material was observed during the watching brief, the bulk of material being demolition (opus signinum and tile) associated with the Roman mausoleum (Scheduled Monument, Roman Round Building, NHLE 1002195). In addition to the demolition material, two features were observed, both in foundation trench 2; the first a greensand and mortar wall foundation, and the second a modern soakaway. No in situ structural evidence of the mausoleum was observed during the watching brief. It is likely that the wall foundation is Roman and may be a structure or boundary wall associated with the mausoleum.<1>