Small tunnels and shafts up to 30m deep were hand-dug under the building’s raft foundation and 62 existing columns. Located on the junction of Holborn Viaduct and Snow Hill, developer Dominus, with architect Stiff + Trevillion, is building a 669-bed, 12-storey student accommodation block. The Central line runs under Holborn Viaduct just metres from the site on the south side and there is a redundant Post Office railway tunnel to the north. The challenge was the historical accretion of old structures and Network Rail infrastructure between the superstructure and the pile. “There was no need for Network Rail to take out redundant services when these were upgraded.