The Norman Castle of Salemi was built by Roger the Norman in 1077 approximately, on existing fortifications greco-roman and arabic. It was remodeled by Frederick II of Swabia in XIII century. In 1789 it was used as a prison, and on 14 May 1860 by this castle Garibaldi lift (on the round tower) the tricolor flag, proclaiming Salemi "capital of Italy" and the dictatorship Garibaldi. From 1934 it became a municipal library.
The castle has a plant unitary enough. Preserves three angular towers, a cylindrical (west) and two square (east, south). None of the square towers exceeds the height of the top terrace of the cylindrical tower, still today the highest point of the city. Today it houses a museum and there are concerts and conferences.