I thought you guys might like this. It is an amazing survey of underground caves.

From the website:

"The Nottingham Caves Survey is in the process of recording all of Nottingham’s 450+ sandstone caves. The project is now underway and we are surveying caves even as you read this. Keep checking the website for newly- surveyed caves! You can read more about the caves, see photographs, watch fly-through videos and take virtual tours by clicking the links on the Cave Map below, or using the thumbnail links to the right."

http://nottinghamcavessurvey.org.uk/index.htm