The precise extent of the underground city, called Caves of Camerano, is unknown, because it hasn't been fully assessed. Extends roughly under the entire historical center, also outside the borders of the ancient fortified city. There are also other hypogea in the territory of Camerano, however placed outside the inhabited center. These additional tunnel, popularly called "holes of the devil" would be the remains of an ancient underground aqueduct that travels along the slopes of Monte Conero. This hypogeum has elements of similarity with other hypogea, such as those of Osimo and Orvieto.
The oldest readable date inside of the hypogeum is 1327. In a first period, the hypogeum must have been recently extended and its functions mainly water, extraction of sandstone building purposes and a burial site. Hereinafter, the hypogeum was subject to a continuous reuse, with consequent expansion and change, so much so that today it is difficult to recognize the different interventions. Beyond some areas where it is still possible to see the exploitation as stone quarry, with traces of some stones of incomplete processing, today a large part of the Hypogeum consists of halls well finished and decorated rooms. Of particular interest are the three round, places clearly designed for meetings. Difficult interpretation is instead the hall called Burchiani, from plant to Ankh.
In the eighteenth and nineteenth century noble families were interested again at these hypogea, making wine cellars, but also places of meeting for secret societies, ridecorandole with new motifs and themes. Only toward the end of the nineteenth century is spread by the family Mancinforte a first mapping, but comprises a minimum part of the underground city, one below the palace of the family itself.
The first awareness to collective level of the vastness of the hypogeum takes place in July 1944, when used as a refuge from bombardment of the surface in the course of the second world war. The entire population of Camerano, estimated at around 2000 people, took refuge in the hypogeum for a period of 18 days.