The late Iron Age oppidum of Calleva underlies the Roman town at Silchester. Excavation (1997-2014) of a large area (0.3ha) of Insula IX revealed evidence of a rectilinear, NE/SW-NW/SE-oriented layout of the interior of the oppidum, dating from 20/10BC, with the remains of the larger part of one compound separated from its neighbors by fenced trackways. Within the compound was a large, 47.5m long hall surrounded by smaller, rectangular buildings associated with groups of rubbish pits. A concluding discussion characterizes the oppidum, integrating and contextualizing a series of major contributions reporting the pre-conquest finds and environmental evidence with the structural story.