Sassari, Church of the Holy Trinity

The church dedicated to the Holy Trinity is located at the confluence between Piazza Mercato and Corso Trinità, outside the historic walls of the city, in front of the ancient Rosello Gate.
The religious Order of the Trinitarians had its first settlement in the city of Sassari on Monte Rosello, as attested by some documents from 1632. In 1640, the Order came into possession of the site overlooking the Rosello Gate, where the church is currently located, and for a long time the date was considered the post-Quem term for its construction.
However, precise documentary evidence has demonstrated that the construction of the building and the adjoining convent structure (today no longer existing because it was demolished in the 1840s), was to be placed within the first quarter of the 18th century. In fact, the new factory is mentioned for the first time in a will from 1708, and from 1710 it is the document that allows us to know the name of the construction director, Antonio Mela, one of the most important and active mastermasters-entrepreneurs of the first half of the 18th century. The church was still under construction in the years 1718 and 1727 and it can be assumed that the work was now completed around 1729, the year in which the Mela was involved in the church and convent of Carmel in Sassari.
The façade is divided into two orders by a richly decorated marcapiano frame. The lower order, divided into three mirrors by Tuscan pilasters, has a single portal with a broken curvilinear tympanum within which, with careful respect for symmetry, the Trinitarian sign is placed straight on the sides by two angels surrounded by a dense ornament of girdles. Above the sign, and within the frame, there is a bas-relief depicting, among ornate phytomorphs and angels, the two saints of the order, Saint John of Matha and Saint Felix of Valois, kneeling on the sides of the deer with the cross on their foreheads.
The system has a single-bay room divided into three large bays of Tuscan piles with a capital; on the molded frame, which also continues into the apse chapel and resting on the pilasters, all decorated with a band with rosettes and boxes carved in high relief with phytomorphic motifs and angelic heads, the barrel vault punctuated by two transverse arches and lunettes within which the quadrangular windows are placed.
The square-shaped apse chapel, narrower and lower than the nave, is connected to the room by a particularly high round triumphal arch, above which is an oval oculus. The side chapels, three on each side and shallow, have all-round access arches surmounted by three rosettes, and are in everything similar to those of the church of Sant'Antonio Abate in Sassari.
In the first decade of the twentieth century, the church was affected by some changes that involved the expansion of the third chapel in the upper street, the decoration of the apse in neo-Gothic style and the introduction of a box in the center of the vault.

History of studies
The church is the subject of a brief summary in Salvatore Naitza's volume on late seventeenth-century and purist architecture (1992).

Bibliography
V. Angius, entry “Sassari”, in G. Casalis, Historical, Statistical and Commercial Geographical Dictionary of the States by H.M. the King of Sardinia, XIX, Turin, G. Maspero, 1849, pp. 71-375;
E. Costa, Sassari, I, Sassari, 1909; V. Mossa, Sassari Architectures, Sassari, Gallizzi, 1965; A. Cesaraccio-V. Mossa, Sassari and its face, Sassari, Carlo Delfino, 1983;
S. Naitza, Architecture from the late 17th century to purist classicism. Nuoro, Ilisso, 1992, sheet 8;
M. Porcu Gaias, Sassari. Architectural and urban history from its origins to the 17th century, Nuoro, Ilisso, 1996;
W. Paris, Sassari, the churches. Artistic, religious and historical itineraries, Sassari, 1997;
A. Sari, The Church in the Archdiocese of Sassari, series “Churches and Sacred Art in Sardinia”, Sestu, 2003.