Lookouts and Cannons
Air Raid Shelters
Military Equipment Storage
Today, there is very little need for military fortifications on the island, especially since the British Navy has greatly reduced its numbers there. The tunnels haven’t been abandoned entirely, however, and many of them have been opened up for visitors to explore.
"very little need?" - WW3 in on the horizon.
Isaiah 33:16 He shall dwell on Sion: his place of defence [shall be] the Fortress of Rock: bread shall be given him; his waters [shall be] sure.