The Latin sources mention Chiusi as one of the most ancient Etruscan cities.
The city is therefore famous for its necropolis, which occupy the hills and which act as a belt to the current town.
In the cultivated countryside and in the woods, over the centuries and especially in the nineteenth century, over a thousand graves were brought to light.
The burials are dug into the soft sandstone, which, if it is true that allowed even the wooden structures of the houses to be reproduced and to paint the walls, has nevertheless facilitated its degradation, due to its lack of consistency, so as to make it advisable to limit the access to some of the most famous hypogea.
The most important are: the Tomb of the Monkey (480-470 a.c.), the Tomb of the Lion (510 a.c.) and the Tomb of the Pilgrim (used from the 4th to the 2nd century BC).
The underground of the historical center is crossed by a dense network of Etruscan tunnels, connected with ancient wells and cisterns and often readapted over the centuries to warehouses and cellars of the palaces above. In Chiusi, the visit to this complex underground system also offers suggestions linked to the legend of Porsenna.
The Labyrinth of Porsenna is substantially a series of tunnels of probable Etruscan age that intersect almost all of Chiusi old and that were excavated in order to drain rainwater. In the labyrinth the mythical tomb of king Porsenna was not found, according to Pliny, who had been buried under the city of Chiusi in a monument with a base of 90 meters on each side and which contained a labyrinth surmounted by pyramids and a bronze cover.