The Fort can be visited
Cliffe Fort
Cliffe Fort is a historic fortification located in the marshland of Cliffe village in Kent, England. Situated directly on the banks of the River Thames, it once served as a crucial part of a defense network designed to protect the British capital, London.
History+
Construction of the fort began in the 1860s, following recommendations from the Royal Commission on the Defence of the United Kingdom. Its purpose was coastal defense in this marshy area. By around 1870, Cliffe Fort was completed and armed with heavy cannons such as the RML 12.5 inch 38 ton gun and RML 11-inch-gun. Modernization efforts took place between 1895 and 1906. In 1890, launching ramps for Brennan torpedoes were added, which are still visible today at low tide. The fort was armed during World War I and served as an anti-aircraft base in World War II.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://de.wikipedia.org/wiki/Datei:CliffeFort0296.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: 51.4636, 0.4559