In the Italian province of Ancona, in the Marche region northeast of Rome, there are two towns just 10 kilometers apart, called Osimo and Camerano. Both share a peculiar common characteristic, having a considerable network of galleries and tunnels under their urban area.
In the case of Camerano, the underground complex is so large that it is called city . Its exact extent is not known because it has never been fully explored, but some believe that its galleries could even connect with those of the town of Osimo.
One piece of evidence is the known existence of other hypogea located outside the town center and the limits of the old walled city of Camerano. These additional tunnels could be the remains of an ancient underground aqueduct that ran along the slopes of Mount Conero.
The complex, which reaches 20 meters deep, is artificial, not natural, and the earliest legible date found inside the hypogeum is 1327. However, analyzes of the structures and the construction techniques suggest they may date back to protohistoric or even prehistoric times.
It is believed that originally it could have been a kind of quarry from which sandstone was extracted for construction. But then it was expanded over the centuries with tunnels and galleries, corridors and decorated rooms, three rotundas for meetings and even a room in the shape of an ankh (the famous Egyptian ansada cross, with the top in the shape of an oval).
The local nobility enlarged and embellished them during the 18th and 19th centuries, using them as a meeting place. It was at the end of the 19th century that the first cartography of some of the passageways was made, those that ran under the Mancinforte family palace.
The so-called Ricotti Cave is one of the most interesting, both for its aspect of an underground church as for the fact that it is located precisely under the remains of the church of San Apollinaris on the surface, built before the year 1000 AD. and attached to the medieval castle.
The last collective use of the hypogeum was in July 1944, when the entire population of Camerano (about 2,000 people) took refuge there for 18 days.
In the same way, the city of Osimo is covered by a network of galleries just as dense and extensive as that of Camerano, excavated on several levels with underground spaces often connected vertically by means of shafts or chimneys that can be traversed.
This labyrinth is made up of some 88 rooms, some of them circular, which extend on both sides of a passageway about 9 kilometers long, with another ten smaller narrow tunnels that connect the subsoil of various palaces in the town.
The decoration here is more profuse, with bas-reliefs of a religious nature in some rooms, and some unusual symbolic motifs, such as elephants or a mermaid with two tails. In some rooms there are decorative motifs that some associate with the Templars, the Knights of Malta, and even initiation rituals of mystery cults.
In both towns there is the possibility of taking guided tours of the caves, which are one of the main tourist attractions in the area.