The sandstone cliffs beneath Nottingham are riddled with over 450 caves, scratched out of the soft material. You can tour some of them, but most of them are off limits and badly mapped.
Not for long: the Nottingham Caves Survey is using laser rangefinders to map and model the Nottingham caves and releasing video flythroughs as they go.
I once visited Nottingham and was impressed by the weird tourist stuff. One cave tour leaves from a shopping centre in the middle of town — you go down and down a spiral staircase in the middle of the mall and end up in an ancient, dimly lit series of caverns. And then there was the epic, homemade Robin Hood dark ride that mixed about 10,000 words of voiceover narration with dozens of extravagantly weird impressionistic mannequins. Hooah!
The Sandstone Caves of Nottingham
(Thanks, Cmpalmer, via Submitterator!)