Colchester Archaeological Trust (CAT) monitored the excavation of foundation trenches for a temporary art installation in Lower Castle Park, Colchester. The site work comprised the construction of a concrete foundation of four linked concrete pads (CBC planning application F/COL/10/1737). <1> The turf was removed from the excavation area prior to the excavation of the 600mm deep foundation trenches. The topsoil layer was 160mm deep including the turf. Beneath the topsoil was alluvial silty clay roughly 400mm deep (L2). L2 was a light, mottled grey/brown/orange colour, and contained very rare inclusions of stone, charcoal and CBM. Two archaeological features were identified during the watching brief, both in the southern foundation trench. F1 contained frequent stones, sand, and brick and tile fragments. Based on the profile observed in the eastern trench edge, F1 appeared to be a shallow ditch. The southern edge of F1 was beyond the southern limit of excavation. Frequent fragments of Roman brick and tile were recovered from the feature (a selection of which were retained). Of particular interest was a large fragment of Mammata, tile which are not particularly common from excavations in Colchester. A few fragments of peg-tile were also recovered from the upper fill of the feature. The feature is visible on Google Earth as an east to west orientated linear that joins a north-south linear to the east. An examination of historic maps of Colchester show these features to be old field boundaries or drainage ditches which divided the land in the post-medieval period and possibly earlier. They have been subsequently infilled, with considerable Roman material incorporated in the infill material. A square shaped pit was identified beneath F1, and its northern edge appeared to be beyond the southern limit of excavation. The pit contained frequent large building material fragments in a mortar rich fill. The building materials consisted of Roman brick, septaria and worked limestone. Two fragments of modern pottery were recovered from the vicinity of this feature and are either associated with F1 or, more likely, F2. As such, it is probable that the building materials were placed into the pit after it had been dug into the base of the boundary/drainage ditch F1.