Fort Darnet - Credit: Wikimedia Commons
Fort Darnet, is a nineteenth-century military installation on the River Medway in Kent, England, that formed part of the defences of Chatham Naval Dockyard. Fort Darnet, like its twin Hoo Fort upstream, was built on the recommendations of the 1859 Royal Commission on an island covering Pinup Reach, the inner navigable channel of the River Medway. Read more on Wikipedia
Source: en.wikipedia.org