The Co-Cathedral of San Siro is the oldest religious building in Sanremo and one of the leading examples of Romanesque-Gothic architecture in western Liguria. Located in the historic center, it was built in the twelfth century, in the place where the bishop Siro would usually celebrated mass. The building, in its current form, is attested from 1143. In 1544 it underwent a raid by Turkish pirates led by Khayr al-Din Barbarossa, who destroyed the altar; since the seventeenth century, a number of changes have transformed the primitive Romanesque structure in Baroque. In 1753 the bell of San Siro (nicknamed "Bacì") rallied citizenship against the Republic of Genoa, whose commander, for punishment, ordered the demolition of the bell tower, rebuilt in Baroque style. The restoration work of the ancient Romanesque appearance began in 1901, designed by Antonio Capponi; 30s were built in the aisles red larch and slate roof; in the 70s, the apses, to recover the Medieval parts. During the reconstruction works of the bell tower, were found traces of an earlier church, before the year 1000. The two side doors, with their reliefs, are the oldest part of the Cathedral. The altar is surmounted by a Black Crucifix (XV century) and a statue of Our Lady of the Rosary, by Anton Maria Maragliano.