The New Armouries was built against the medieval inner curtain wall at the Tower of London in 1663-4 as a small arms store, and was later used for displays of the Royal Armouries collections. On the opposite side of the curtain wall a range of buildings providing soldiers' houses was constructed in the mid 17th century. This was rebuilt as the Irish Barracks by Dugal Campbell in the 1750s, but was demolished during the 19th century. Oxford Archaeology carried out a programme of archaeological and building recording at the New Armouries and Irish Barracks during redevelopment works by Historic Royal Palaces between 1997 and 2000. Excavations found traces of Roman deposits, and the remains of medieval buildings and features constructed within the royal garden. The complete plan of Dugal Campbell's Irish Barracks was revealed. This Occasional Paper contains a full account of the archaeological results and building surveys, a discussion of the historical and cartographic evidence, and reports on finds and environmental remains.