with  NiaDebesis

"Tank Plateau" is the english translation of this place's italian name, traditionally given because there's a huge aquifer under it.
The plateau is made by a layer of tuff, coming from the eruptions of the sorrounding mountains (extinct volcanoes). Under the rock, there's porous terrain: water remain trapped there, underground.
Since the presece of this water reservoir, Etruscans built an important settelment on the plateau, where there are still some ancient tombs (the village itself was built out of wood, so no remains survived today). Etruscan cities were always built where there was water easily availabe as it was, for example, the ancient city of Viterbo with the Urcionio river.
A sunken road, cut in the tuff layer, survives too leading to the tombs area from the plateau ridge.