CHIUSI, a town of Italy, in the Tuscan province of Siena, situated on a hill, and not far from the Lake of Chiusi. It is a bishop’s see, and has a large cathedral, but is chiefly interesting for the Etruscan bronzes, mirrors, vases, and funereal urns found in the vicinity, of which its museums contain collections. Chiusi, the Clusium of the Romans, was one of the twelve cities of the Etruscan confederation, and was the headquarters of Porsena. After the decay of the Roman power it sank in importance, and in the Middle Ages malaria greatly reduced the number of its inhabitants; of late years, however, the prospects of the place have greatly improved, in consequence of the drainage of the marshes in the neighbourhood. Population, 6460.