In the Quinto Alto locality are still to be found two of the most important Etruscan architectural monuments: the great tholos tombs (with false cupola) of Montagnola and Mula. They owe their fame to the splendid state of conservation of the structures, which bear witness, for the orientalizing age (7th century B.C.), to the utilisation of an architectural technique similar to that of the monumental tombs at Mycenae, among them the so-called Treasure of Atreus.

As compared to other false-cupola tombs – those of Populonia, for instance – these tombs differ not only in the circular layout of the main chambers, but above all in their remarkable size: a diameter of 5 metres for the Montagnola Tomb, over 8 for that of Mula, dimensions involving notable technical difficulties as regards construction and stability.

The Montagnola Tomb appears as a tumulus with diameter of nearly 70 meters, originally bounded by blocks of clay-rich limestone and waterproofed by a layer of clay. It is entered through an open dromos (corridor) leading to an inner corridor with pseudo-vault, on either side of which are two small rectangular cells. A narrow ogive door opens into the main chamber, which is covered by rows of progressively projecting slabs of stone resting on a vertical socle 3 meters high. The summit is closed by a square slab supported by a pilaster, which, however, does not seem to have a true static function.

Entirely without a central support is the great tholos of the Mula Tomb, which was incapsulated in the sixteenth-century Villa Garbi Pecchioli to be used as a wine-cellar. With part of its dromos demolished on that occasion, it differs from the Montagnola Tomb in that it has no socle in the chamber. Perhaps constructed by the same workers as the other tomb, it boasts the largest cupola known as of now in pre-Roman Italic architecture.