Sciacca, town, southern Sicily, Italy, northwest of Agrigento. On the site of the Roman Thermae Selinuntinae, it has been, from antiquity, a health resort with hot sulfur springs. The coastal town has a modern appearance, but notable older structures include the town walls (1336; rebuilt c. 1550), the ruined castle of Luna, the 14th-century Palazzo Steripinto, and the 14th- and 15th-century Church of Santa Margherita. Sciacca is an agricultural centre and has a fishing harbour. Pop. (2006 est.) mun., 40,868.