A new project has been launched by archaeologists and historians from the University of Nottingham to make the city’s medieval underground cave network the focus of a regeneration plan for the city. The City of Caves Project that plans to highlight the city’s history as part of the regeneration of the Broad Marsh area is one of the biggest city center redevelopment projects in Europe, according to a press release by the university .
Source: Ancient Origins
There's an interesting article, on the same website ('Ancient Origins'), about the mysterious Margate Shell Grotto, which I visited about 30 years ago. It's a sort of subterranean temple covered in tens of millions of shells, and located a few miles away from the coast underneath a very ordinary looking English suburb. Nobody is sure when it dates from, or what its purpose was (I thought it had a temple vibe).