The Castle can be visited
Durlston Castle
On Durlston Head near Swanage in Dorset, England, stands Durlston Castle. Originally built as a folly, it served as a restaurant and is now a destination on England's south coast.
History+
The creation of Durlston Castle is closely linked to local stone merchants John Mowlem and his nephew George Burt, who aimed to develop Swanage as a tourist destination. In 1862, George Burt acquired the hills around Durlston Head, an area already home to quarries. In 1887, Burt had a small castle built on the hill, intended to serve as a restaurant for guests of his estate. The plans were drawn by G. R. Crickmay from Weymouth, and construction was carried out entirely from local stone by W. M.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://en.wikipedia.org/wiki/File:2012-07-25_Durston_Castle_main_entrance.JPG
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 50.5951, -1.9532