This is one of those exceptional places that only Matera can offer. This calcarenite quarry, mined from the 14C-16C, is a masterful example of the "negative architecture" that characterises the Sassi. Discovered in the 1990s after a long period of neglect, Casa Cava has become an underground cultural centre with an extraordinary auditorium, cut out of the rock, that offers unforgettable concerts. Not to be missed.