Frasassi caves are underground caves that are located in the municipality of Genga, in the province of Ancona. The cave complex falls within the Regional Natural Park of the Red Gorge and Frasassi. The complex is formed by a series of caves of which the first, visited by the current input, is the chasm of Ancona, huge cavity that has an extension of 180 x 120 m and a height of 200 m; It is so large (more than 2 million m3 of volume) than inside it could be smoothly Milan Cathedral. Since 1972 it is under the protection of the Frasassi Consortium, consisting of the town of Genga and the Province of Ancona, with the aim to safeguard and enhance the usability of scientific and tourist. From 1 September 1974 of the caves it is open to the public, becoming in time one of the major tourist attractions of the Marches; it is estimated that since then over 12 million people have visited the.