Excavation was carried out to investigate a large building in the north-east of Isurium Brigantum. The structure was first excavated in 1924 during investigations of the defences, but the full extent of the building was revealed in the geophysical survey. The re-excavation of the 1924 trench set out to investigate the chronology and use of the building and its immediate context. The building is thought to be a warehouse (horreum) constructed around AD250-270. Its destruction came in the mid-fourth century or later. This huge warehouse sheds new light on the role of Isurium Brigantum as a centre for trade, taxation, and storage.