If you fancy a journey to the centre of the earth, visit the Frasassi Caves, located near Genga, about 60 kms from La Mela Rosa. They are one of Italy's largest complex of caves.
Marche Voyager - Guide to the Frassai Caves says: Some 13 km of limestone caverns have so far been explored and it is believed that they may run for up to 35 km. Only one and a half km of this crystalline wonderland is open to the general public. Equipped with walkways and theatrical lighting, it includes the awesome Grotta Grande del Vento, Europe's largest single cavern, so vast that Milan Cathedral would fit comfortably inside, and some of the most extravagantly fanciful stalagmites and stalactites you are ever likely to see.
The guided tour takes about an hour and is well worthwhile.