The Fort can be visited
Fort Luton

In Kent, England, near Chatham, lies Fort Luton. As part of a defensive ring intended to protect the overland approaches to Chatham, it is the smallest of the five late Victorian land front forts.
History+
The construction of Fort Luton was planned in the course of the 1859/60 Royal Commission on the Defences of the United Kingdom but was initially postponed for cost reasons. Only in 1872 was the land acquired, and in 1876, after parliamentary approval, construction began under the supervision of the War Office. The work, which also involved convict labor, was protracted due to a lack of funding and the frequent change of workforce. An original design by W.F. Jervois was later modified, with a quarter of the facility, including the main magazine, being omitted. Completion finally occurred in 1892.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://en.wikipedia.org/wiki/File:Fortlutonchatham.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: 51.3659, 0.5305