Liverpool's lost Williamson tunnels unearthed
11 March 2013 Last updated at 00:32 GMT
Volunteers in Liverpool are giving up their free time to clear out a mysterious labyrinth of tunnels that lurk beneath the city's Edge Hill area.
The Friends of the Williamson Tunnels are removing the results of decades of Victorian "fly-tipping", hoping one day to expose tunnels which they believe could stretch for miles.
The tunnels were built and conceived in the early 19th century by eccentric businessman Joseph Williamson, who paid soldiers returning from the Napoleonic war to build them. No records were kept of how far they stretch, nor which direction they go in.
After Williamson's death in 1840, the tunnels fell into disrepair. The site currently being cleared was filled with over 100 years' worth of ash and debris from a local bakery.
BBC News was given a tour by volunteers who explained why they are so intrigued by Williamson's weird and wonderful world.
Video Journalist: Dan Curtis