Alcamo, a city of Sicily, in the province of Trapani, 23 ra. S. W. of Palermo; pop. in 1872, 20,890. It was originally a Saracenic town, built on the summit of a neighboring hill. The Saracens were expelled in 1223, and the town was rebuilt at the foot of the hill. It is surrounded by a battlemented wall of the 14th century, but the place is very poor and decayed. In the vicinity are the ruins of ancient Segesta and quarries of yellow marble.