The following text is from the original listed building designation:
MARINE PARADE 1. 5282 (South Side) Marine Town, Sheerness Grotto-shaped folly to north-east of Ship on Shore Public House TQ 97 SW 11/81
II 2. Circa 1830. This Grotto was built by a farmer who found a ship's cargo of cement in barrels washed up on the coast. As the barrels had become soaked with sea water the cement had set to form barrel shaped blocks which were used to build the folly's walls. 1 storey built of cement blocks, flint and burr bricks. 5 pointed arches, now filled in by weatherboarding. Parapet with a succession of curves.
Listing NGR: TQ9354674882

Description from record TQ 97 SW 1024:
c1830 grotto shaped folly built from washed up ship's cargo of cement which had set into barrel shaped blocks. 1 storey of cement blocks and flint and burr bricks. 5 pointed arches, weatherboard filling. Parapet with succession of curves. (1)

First shown on 2nd edition OS 25" mapping (1897-1900).

A heritage assessment of a nearby site noted that The Grotto does not appear on an 1840 or 1869 map, and its first appearance is on a map from 1899 suggesting that it may have been constructed later than originally thought. The assessment also notes that the ship which is supposed to have carried the cement used to create The Grotto (The Lucky Escape), ran aground in 1848 which does not correspond with The Grotto's first potential date for construction between 1869-1899.
A timber figurine was once placed on the northern end of the roof; the form of the figurine is not included in the report. (3)

<1> Department of the Environment, KCC Greenback Index (Index). SWX9400.

<2> English Heritage, List of Buildings of Special Architectural or Historic Interest (Map). SKE16160.

<3> HB Archaeology and Conservation Ltd, 2016, Seabreeze Caravan Park, Marine Parade, Sheerness, Kent: Heritage Impact Assessment (Unpublished document). SKE52828.