The cornerstone in the evolution of Romanesque architectural forms was the basilica of San Gavino in Porto Torres. Among the most relevant examples there are the cathedrals of Sant'Antioco di Bisarcio (Ozieri), San Pietro di Sorres in Borutta, San Nicola di Ottana, the palatine chapel of Santa Maria del Regno of Ardara, the Santa Giusta Cathedral, Nostra Signora di Tergu, the Basilica di Saccargia in Codrongianos and Santa Maria di Uta and, of the 13th century, the cathedrals of Santa Maria di Monserrato (Tratalias) and San Pantaleo (Dolianova). As for military architecture, numerous castles to defend the territory were built during this period. At the beginning of the 14th century date the fortifications and towers of Cagliari, designed by Giovanni Capula.