One of the more creative uses of an abandoned clay pit is The Eden Project, a huge garden complex with two massive bio-domes, each with an artificial climate.

The outdoor gardens.

Inside the semi-tropical bio-dome.

Inside the tropical bio-dome. This is the larger of the two. The brochure informs us that the Tower of London could fit inside of it. I think that's a grand idea; it would probably bring in more tourists.

A new attraction at the Eden Project is the Zip Ride. For ten quid they will strap you into a harness and send you zinging along a wire stretched high above the complex. It's a great way to see the whole place in about 30 seconds; I know because I did it.