a seaport of Tuscany, Italy, in the province of Pisa, 8 m. by rail W.S.W. of Campiglia Marittima (which is 53 m. S.S.E. of Pisa), 62 ft. above sea-level, at the southern extremity of the peninsula of the Monte Massoncello. Pop. (1901), 5979 (town); 7703 (commune). It is surrounded by old walls, and contains some interesting Renaissance works by a master of about 1458 under the influence of Alberti. It is the port of embarcation for Elba, the nearest point of which is about 6 m. to the south-west, and originally belonged to Pisa. It gives the title of prince to the Buoncompagni Ludovisi family, who, however, no longer own it.