Qualche cenno sull'argomento:

Saint Mary’s church became the city Cathedral in 1258, after conquering and then abandoning Saint Igia, the capital of the Giudicato di Cagliari (the Sardinian district of Cagliari), the Episcopate’s  main venue. The square base of the bell tower, the arms of the transept, the two Romanesque style side doors (the southern one) and the so-called Pisan Chapel, devoted to the Sacred Heart and located on the left side of the quadrangular presbytery, are the only parts of the Medieval church. Symmetrical to the Pisan Chapel, an elegant XIV century chapel was built in Gothic-Aragonese style, dedicated to the Sacred Thorn. The first transformation of the Cathedral took place between 1664 and 1674 and was directed by the Genoese architect Domenico Spotorno, who completely renovated and widened the interior surface. On that occasion, the two medieval chapels were hidden. Numerous stone-cutter masters, authors of the beautiful tiles that decorate the archway soffits, participated in the restauration process. In 1702 the architect Pietro Fossati began the façade renewal, adapting it to the Baroque taste of the time. The renovations ended the following year.

Finally, during the last and final restoration by the architect Francesco Giarrizzo in 1930, the church unveiled the two hidden XIV century chapels and acquired its current Neo-Romanesque façade, built with calcareous stones and replacing the former Baroque façade, covered in marble and demolished in 1902-1903.

Under the presbytery of the Cathedral in 1618, the Archbishop Francisco Desquivel decided to build a crypt with a sanctuary: three large interconnecting parallel chapels, entirely covered in inlaid polychromous marble, aiming at preserving the holy relics of Cagliari’s numerous martyrs, which had been found since 1614.