CHIUSI, a town of Tuscany, Italy, province of Siena, 55m. S.E. by rail from the town of Siena, and 26m. N.N.W. of Orvieto by the main line from Rome to Florence. Pop. 2,307 (town), 6,746 (commune) . The ancient name was Clusium (q.v.). It is on a hill 1,305ft. above sea-level, and is surrounded by mediaeval walls, in which, in places, fragments of the Etruscan wall are in corporated. The cathedral of S. Secondiano is a basilica with eighteen ancient marble columns. It has fine choir books from Monte Oliveto Maggiore (see AscIANo). Chiusi was devastated by malaria in the middle ages (see CHIANA). Nine miles by road to the north-west are the baths of Chianciano with important springs (which are especially valuable for liver troubles) and several hotels.