Inner city caving

Climbing walls are commonplace, but what about artificial (and inner city) equivalents for other outdoor pursuits? How about an artificial cave that could be used to give people a taste of caving, and to train them, in a safe and accessible environment.

It should be possible to make an artificial cave with moving walls (to add some variety and allow difficulty levels to be varied), bolt-in handholds (for the rock climbing element) and underwater parts (to simulate cave diving).