Consecrated by Bishop Didacus Cugia on May 9, 1688, it was built in three years to the design of architect Domenico Spotorno, who died in 1684 and is buried in the Cathedral. The Baroque-style exterior façade includes the majestic dome and two symmetrical bell towers, which are accessed from the unusual exterior loggia, topped by a large terrace. It was built on the ruins of the ancient cathedral, which was built on a pre-existing monastic church around the year 1000 and collapsed, at the ne of a long period of transformations, in 1683. The interior includes six chapels, the largest of which form the transept, transverse to the nave, which has a crypt. The cathedral is rich in marble and frescoes: those on the dome date from 1954 and are the work of Alerese artist Peppinetto Boy. The elevated altar and apse, equipped with a wooden choir, are accessed by a central and two side staircases. Also of note is the 17th-century wooden organ.
