From the homonymous Cagliari hill of Bonaria, the sanctuary and the basilica dominate the Gulf of Cagliari. The area corresponds to a sector of the necropolis O of the Roman city, in which some Christian tombs were found in the nineteenth century, the oldest found in Cagliari. The Aragonese settled on the hill between 1324 and 1326, after the granting of the “Regnum Sardiniae et Corsicae” to the Crown of Aragon by Boniface VIII, to besiege the Castle of Cagliari and then put an end to Pisan hegemony.
The sanctuary of Our Lady of Bonaria is one of the symbolic places of Cagliari's identity. From the top of the homonymous hill, it is one of the first buildings seen from the sea, entering from E into the wide bay overlooking the city. It is no coincidence, therefore, that Our Lady of Bonaria was elected protector of sailors. His highly venerated wooden simulacrum, according to tradition, landed inside a box on the Cagliari coast in 1370, dates back to the second half of the 15th century and is the valuable work of an Ibero-Campanian sculptor.
The church was founded during the years of the siege that the Aragonese placed on the Pisan Castle of Cagliari, between 1324 and 1325. The surrender of the district to the Crown of Aragon, in 1326, also determined the end of the citadel of Bonaria, but not of its sanctuary, originally named after the Holy Trinity and the Madonna, which represents a direct derivation of the Gothic-Catalan models. In fact, it was modeled after the chapel of Sant'Agata, included in the Palazzo Reale Maggiore in Barcelona (1302-11). The only exception is the unusual solution of the bell tower raised above the presbytery, probably as a watchtower, included in the walls that protected the Aragonese citadel.
The classroom is about 15 m long. Originally it was shorter, with a single nave with a polygonal apse. In the typical ways of Gothic-Catalan architecture, it had sturdy buttresses along the outer walls. During the 16th century, the side chapels were opened among the buttresses. Only those on the left side are preserved. The roof, originally wooden, was replaced by an ovival barrel vault covered by grooves. In the 18th century, the chapels on the right side were demolished, of which today only the access arch to the Basilica remains. The restorations of 1869 distorted the original structure of the Sanctuary, which was lengthened to align it with the basilica, begun in 1704 and completed only in 1926.
The presbyterial area, the only survivor of the 14th century church, has a semi-decagonal plan, with an umbrelliform cross vault. Outside, leaning against the apse, you can see the fortified bell tower. The roof, built in the 19th century, is barrel-vaulted. In the façade, rebuilt in limestone, the jambs and the molded ogival arch, which constituted the portal of the destroyed church of San Francesco di Stampace, have been reassembled.

History of studies
The importance of the monument was highlighted by Renata Serra (1957, 1984), who recognized it as the oldest Gothic-Catalan architecture in Sardinia. The historical research of Antonio Arribas Palau (1952) established that the sanctuary factory is part of the fleeting urban settlement on the hill, wanted by the infant Alfonso during the years of the Aragonese siege of Cagliari. The sturdy wall, according to Joaquin Arce (1960), could have incorporated the church bell tower. Francesca Segni Pulvirenti and Aldo Sari (1994), in line with previous studies, believe that the sanctuary was built between 1324 and 1325.

Bibliography
E. Lippi, History of the Sanctuary of Our Lady of Bonaria, Cagliari, 1870;
A. Arribas Palau, The Conquest of Sardinia by Jaime II of Aragón, Barcelona, 1952;
R. Serra, “The sanctuary of Bonaria in Cagliari and the beginnings of the Catalan Gothic in Sardinia”, in Sardinian Studies, XIV-XV, 1955-57, part II, pp. 333-354;
J. Arce, Spain in Sardinia, Cagliari, 1982, p. 353; R. Serra, “The Sardinian-Catalan architecture”, in The Catalans in Sardinia, a
edited by J. Carbonell-Francesco Manconi, Cinisello Balsamo, Silvana, 1984, p. 125;
F. Segni Pulvirenti - A. Sari, Late Gothic and Renaissance-influenced architecture. Nuoro, Ilisso, 1994, sheet 1.