Admiralty Tunnel
The 445th longest tunnel in the world
Admiralty Tunnel is a tunnel in Gibraltar. The tunnel was used for the purpose of bringing stone from the east side. During the Second World War the tunnel contained an operations centre where Dwight Eisenhower planned Operation Torch. As of 2013, the operations centre is used to house a secure data facility.
Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).