The cathedral in the old town centre sits in a large square elevated above street level.
Records of the cathedral exist as far back as 1131, however the shapes and sizes of the original building differ from its current-day appearance. The first structure was probably arranged around three naves, in Romanesque style; altered in 1228 on the wishes of the archbishop Torgotorio de Muru, due to the serious damage it had incurred as a result of continuous sacking and fires caused by the troops of the giudice di Cagliari. The year 1228 is also recorded on the bronze shutters with leonine protomes produced by the craftsman Placentinus.
However, the layout from the XIII century was not its definitive one. The following century, the transept with Gothic style chapels were built. Its current-day appearance was only finalised with the work carried out in the XVIII century.
The sloping facade is split into two rows by the fine cornice: in the lower one, the portal opens out crowned by columns and fragmented gable, while on the upper row, a large monofora with curvilinear gable and two blind niches opens out. The Latin cross layout is arranged on a single nave overlooked by three chapels each side, a transept covered by an octagonal cupola, raised presbytery with marble balustrade and quadrangular apse.
In contrast with the facade which almost appears to be unfinished, the interior is elaborately decorated: there are four Evangelists are depicted in the cupola’s pendentive shutters, while the blessing Christ is depicted in the nave’s vault. The numerous sculptures include the Vergine Annunciata from the XIV century, attributed to Nino Pisano while of the marble altars, the one that stands out is the tridentine high altar and that of Sant’Archelao created by the sculptor Pietro Pozzo in the Eighteenth century.
