The present Romanesque and Gothic structure was first consecrated in 1107 or 1108, but a previous church from the 9th century stood on the site.
The interior has five naves, of which the central one is marked by tall polychrome columns rising two storeys.
On the south, the first chapel houses an 18th-century marble statuary group depicting the Ecstasy of Mary Magdalen by Giovanni Battista Bernero.
A small column monogrammed with the sign of Christ is the spot where the town's patron saint, Evasius, was martyred.
Tradition maintains that if someone puts his or her ear to the column, it is possible to hear the blood of the saint flowing.