The grottos were casually discovered in 1971 by the C.A.I. Speleologic Group of Fabriano-Ancona and the first part was opened to the public in 1974; the explored part is about 18 km. The grotto area belongs to the Regional Park Gola della Rossa and Frasassi, a green oasis where very rare plant species grow, such as the moeringia vescicolosa, and wildlife as the royal eagle, the owl, the peregrine hawk, the wolf, an area which includes 10 ancient communes, and 9 perfectly-preserved medieval castles, all of them well worth a visit especially for the photographer in search of magic, spectacular views.
The grottos were formed through a time span of over 1.4 million years by the Sentino stream which in its descent penetrated with its mineral waters the mountain rocks, and through a corrosion process created the concretions that make the grottos so utterly beautiful. The grottos, which are always at 14 degrees centigrade, can be visited throughout the year, and in summer also at night. So far over 10 million people have visited the grottos and admired this natural masterpiece, the tiny lakes, stalactites and stalagmites, alabaster and crystal arabesques, all made the more precious by the masterly lighting system devised by Carlo Cesarini (Senigallia 1905 - Rome 1996), an Italian scriptwriter of great renown in the 1970's and 80's.