The church is one of the most important examples of Sicilian baroque. It was built onto the ruins of a little church from the 1400's, then enlarged in 1640 and finished in 1726 with the completion of the front, which is covered in statues and decorative stucco work by Giovan Maria Serpotta. The magnificent interior is a Latin cross, with a central nave and two aisles divided by round arches. The internal chapels have two renaissance altar pieces: The Madonna of the Rosary (La Madonna del Rosario) by Vincenzo da Pavia and The Crucifixion Between San Domenico and Mary Magdalene (La Crucifissione tra San Domenico e la Maddalena) by G. Giacomo Fondelli, both painters coming from the region of Lombardy. To the left of the church there is the ex Dominican friary with a cloister built in 1300, characterised by pointed arches on thin coupled columns. Inside the friary there are the Santa Barbara room and the Calendar room which contains a magnificent fresco on the wall of a liturgical calendar, covering the years 1700 to 2192.
The Friary also contains the Museum of Risorgimento and The Sicilian Society of National History (La Societa’ Siciliana di Storia Patria).