(anc. Sublacum), a town of the Papal states in the Comarca, and 34 miles east of Rome, on a hill near the right bank of the Teverone. It stands in the midst of beautiful scenery; but has itself dark narrow streets, lined with old and gloomy houses. On the top of the hill stands an old castle, which was long a summer residence of the Pope. Subiaco has also a handsome church, containing many works of art; and in the vicinity are the remains of a palace of Nero, and a fine monastery. Pop. 6000.