A few kilometers from the crowded Romagna coast, in the Conca valley hinterland, there is a Nature Reserve and the Onferno Caves. This pretty village, perched on the Conca valley hills, was once called “Castrum Inferni”. Over the centuries its name has even become that of Hell in Italian, before dissolving in today’s Onferno. This sinister reference was due to steam smokes that in the winter months, especially at dusk, came out of the rocks letting us imagine that right there the entrance to the underworld was hidden. In reality the phenomenon of this smoking is caused by a thermal difference between the inside and the outside of the cave, but this was only discovered in 1916, when the Bolognese speleologist Quarina first visited the cave.
The karst complex of Onferno is considered among the most important chalk caves in Italy. Excavated by the waters of a small stream, which over thousands of years has made its way through the rock, the caves of Onferno open up at the base of the large and unique chalky boulder on which the Castrum once stood. The cave can be visited with a guide and has a development of about 400 meters, with a drop of just over 60 meters. One of its features is the presence of large colonies of bats (over 8000 specimens). Along the way you come across rooms of different sizes, some very large, others smaller and full of creations. The headquarters of the Nature Reserve is located in the ancient Pieve di Santa Colomba, now restored and used as a Naturalistic Museum which is a real paradise for children; from here a series of nature trails of varying length and degree of difficulty can be followed on foot, by bicycle or on horseback.