Excavations by the Cambridge Archaeological Unit took place on the site of the proposed riverside extension of the Thornton Building, Trinity Hall College. Interpretation of the excavation was augmented by the well-preserved environmental evidence. The earliest deposits were waterlain and indicated that the site originally lay within the river, the gravel bed being found some 2.60 metres below the present water level. The river course was subsequently narrowed and the site was reclaimed by the construction of a riverside wall and northern wall, followed by ground consolidation. Dating evidence showed that this reclamation is roughly consistent with the College’s acquisition of the land. Under College ownership, the site underwent a series of changes. Access to a building beyond the northern wall was subsequently blocked and the site was covered in a cobbled surface. In the 18th/19th century a toilet block was built against a new river wall and connected to a rain water culvert. This sewage system was updated with the construction of the Thornton Building at the turn of the century, but the toilet block continued in use until the Second World War.