The Treasury building is placed between the north wall of St. Andrew's Chapel, which it exactly covers, and the south side-aisle wall of the Infirmary Hall, but is a structure that is independent from them. The Treasury building stands nearly square to the Infirmary wall and measures about 30 feet square.

The Treasury, under the name 'Vestiarium', is shown on Prior Wibert's Map of the Priory's waterworks dated c. 1165. Here it appears as a sub-structure of two open arches, surmounted by an upper storey containing a chamber with windows. It is surmounted by a high-pitched roof, with a ridge and hips. The style of the building is in advance of Prior Conrad's work (1108-1126), but is pure round-arched Norman of a late character, with ribbed vaults. The building is divided into two severies and each has an open arch below for passage on the east and west faces. The storey above which is the Treasury chamber has a high domical vault, the crown of which is 9 or 10 feet above the heads of the window, giving this unique and noble room an internal height of 20 feet. Internally the overall chamber is 24 feet wide E-W by 22 feet N-S. During the late 13th century during Prior Eastry's term (1285-1331) a chamber was added above the Treasury.

The Treasury being important, as a fire-proof repertory for the safe keeping of the rich ornaments, relics, and documents of the church, which had in its early years been deprived of its Papal Bulls and charters by the great fire of 1130.

Willis, R., 1868, 'The Architectural History of the Conventual Buildings of the Monastery of Christchurch in Canterbury' (Article in serial). SKE30206.

Blockley, K., Sparks, M. & Tatton-Brown, T., 1997, Canterbury Cathedral Nave, Archaeology, History and Architecture (Monograph). SKE29723.