Grotto in Carshalton Park

The Grotto in Carshalton Park is an early 18th-century structure, originally conceived as part of the design for Carshalton House by Giacomo Leoni. According to Leoni's published writings from around 1729, it was intended to be a richly adorned feature, "most artfully contrived and adorned with a great number of rarities."

The exterior presents as symmetrical, curved brick walls that gradually rise to a central peak, following the contours of the hillside. Splayed walls flank the center, featuring plain, segmental-headed alcoves. Three round-headed arches, the central one wider and taller, dominate the front; these open into a rectangular vestibule with round-headed niches at each end. Beyond this vestibule is a large, octagonal room with brick walls and a cambered ceiling supported by a coved brick cornice. Inside, a single segmental-headed niche faces the entrance.

The grotto was part of the Carshalton Park estate, the former seat of Sir William Scawen. In 1718, John Aubrey described the existing house as "a handsome old house... with behind it a fine garden adorned with reservoirs of water, also a long and pleasant walk of orange and lime trees and a wilderness." Although plans for a new house by Leoni were never realized, the original grotto remained and was later incorporated into the landscape.

Later alterations have resulted in the loss of original decoration. The brick retaining wall of the long water remains as an exterior feature. Other surviving elements of the former estate include the former orangery in The Square and sections of the park walls.