There's a Network of Tunnels Under the White Cliffs of Dover
The stark face of the White Cliffs of Dover faces France, across the famous Strait of Dover, and during World War II, Winston Churchill ordered that a network of tunnels be dug into the cliff face. After 100 days of work, there was an underground world that could house up to 189 people (4 officers, 185 men) and that included a hospital and bombproof chambers.
In the 1950s, when they were no longer useful, the British military decommissioned the tunnels, and they were filled in with dirt. But recently, they were rediscovered and re-excavated. Now, they're open to the public.
Inside, there's graffiti on the walls, carved by the soldiers who lived there. The team that cleared out the tunnels also found books, tickets to a soccer game, wire hooks, and a thread of khaki wool still attached to a needle.
Tours of the space are guided, and the Guardian warns: The hard-hat descent, lit by handheld and head torches, is described as “an adventure in a dark, dirty and wet environment, and is not suitable for those who are claustrophobic or unsteady.”
Sounds like our kind of afternoon adventure.