The cathedral of the Immaculate Conception is the duomo of Bosa and is characterized externally by two domes, covered with colored majolica, and by squat bell tower in red sandstone, incomplete and laying sculpted the date 1683. The interior has a single nave with barrel vaulted ceiling and divided into five bays by pilasters and arcs cross members, with four chapels on each side. The first chapel on the right is the "Cappellone" of the Sacred Heart, very developed in length and organized as a small Church with himself, perpendicular to the duomo. The the transept chapels are dedicated to St Joseph, to Our Lady of Bonaria, to the souls of the Purgatory. The side walls of the nave are divided into four spans by semicolumns with rich capitals on which rests a trabeation continues on which is based the barrel vault high 17 meters divided into 10 lunettes which correspond to 10 windows. Between 1877 and 1878 was decorated internally by the tempera painting of the Parmense Emilio Scherer depicting Heaven Dante. Last important detail of the Duomo are the two statues of Saints Peter and Paul at the sides of the altar. These two simulacra of 1608 come from the ancient cathedral of San Pietro Extramuros where they were stored in two niches and were exposed on the occasion of the feast. The the transept chapels are dedicated to St Joseph, to Our Lady of Bonaria, to the souls of the Purgatory. The side walls of the nave are divided into four spans by semicolumns with rich capitals on which rests a trabeation continues on which is based the barrel vault high 17 meters divided into 10 lunettes which correspond to 10 windows.