Chiusi had its period of maximum splendour during the reign of Porsenna. There are some important archaeological sites in the area and there is the National Etruscan Museum. In front of this is the 12th century Duomo, which was re-structured in 1585. At the side of the Duomo is the Museum Cattedrale with precious religious relics.
Around the Chiusi area were found some of the most important Etruscan tombs, such as the Scimmia, del Leone, Pellegrina etc. From the beginning of Christianity there are also the catacombs of Santa Mustiola and Santa Caterina in the area, along with the labyrinths which, underground, brought water to the cistern of the city in the lst century AD.