Summerhouse and Underground Vaulted Chamber in grounds of Rookwood Hospital

The summerhouse and underground vaulted chamber are located in the grounds of Rookwood Hospital. This 18th-century structure is designed in a single-storey octagonal "Gothick" style, reminiscent of the work of Batty Langley, and is set on an earthen mound. The external walls are faced with Bath stone ashlar, which is now extensively damaged, while the interior consists of rubble and brick. Each bay features a buttress and a narrow pointed window opening with a hoodmould, although the sash windows were removed as of April 2002, and several openings have been blocked with concrete blocks.

On the south side, there is a square-headed doorway with damaged clustered columns above a short flight of steps, and a lunette with trefoils above it. The structure has a machicolated parapet with battlements, although the original crocketted pinnacles at each corner have been lost. At the base of the mound at the rear, a flight of stone steps leads down to a vaulted chamber beneath the summerhouse.

The interior of this chamber, which may have been intended as an icehouse, features a brick vault and walls made of stone rubble. The chamber was not entered during the resurvey.