The church dedicated to Sant'Apollinare is located in the ancient Pozzo di Villa, a district within the city walls.
The oldest structures of the church of Sant'Apollinare date back to the end of the thirteenth century. Of these, in Italian Gothic forms, the only trace is the shape of the façade portal, walled up during the subsequent reconstruction of the mid-17th century. The expansion works, in fact, took place from the first decade to the fifties of the seventeenth century, and involved a characterization of the entire building in a late Renaissance sense. The façade was built in 1646, as attested by the date engraved on the lintel of the portal, while the roof, almost completed in 1651, when a fire damaged part of the structures, was completed in 1652, after the great plague.
The new factory incorporated part of the previous one, expanding the building on the left, which was almost doubled in width; the right side and part of the façade of the primitive church were used as load-bearing walls; in addition, a different construction technique was adopted, in stones welded with lime and sand mortar, compared to stones and clay mud.
In 1896, following the collapse of the side walls and the damage to the vault, the closure of the church was decided, and in 1898 work began on the demolition of the vault and the consolidation of the structures but, following the progressive failure of the structures, an almost complete demolition and a reconstruction in neo-gothic forms were carried out. Only the bell tower, the apse chapel and the façade were spared. Thanks to a description prior to these reconstructions, it is possible to learn about the structure of the seventeenth-century church, based on the pattern of congregational churches of counter-reform descent, typical of the seventeenth-century churches of Sassari, with a single-naved room turned in a barrel, with three chapels on each side, a quadrangular apse with a barrel vault and a bell tower with a lower square barrel and an octagonal upper barrel, with curved openings and an elongated dome in segments, surmounted by the cross.
The façade, whose geometric ornamentation is borrowed from the church of Jesus and Mary (today S. Caterina, Sassari) and reinterpreted in a Plateresque sense, is framed by two projecting corner pillows with a molded base on a high plinth, and is divided into two orders by a molded frame decorated with a frieze with ovoli and strips. The first, smooth, has a simple rectangular portal with lintels on shelves. The upper one is divided into mirrors by four pilasters resting on the marcapiano frame, of which the central ones are decorated with coffers. Among these is a large blind gable window, with a double frame decorated with classicist ornaments and further flanked by two narrower and lower pilasters, decorated like the largest and surmounted by pinnacles; above the tympanum is a carved cross.
A frame highlighted by dentelli and ovoli closes the second order and is the base of the flat ended pediment, delimited laterally by the continuation of the central boxed pilasters. In the mirror, between two twisted columns, there are two blind windows curved side by side, with a frame adorned with carvings and denticles, above which is the crowning frame, molded and adorned below by a classic palmette-shaped frieze and above by a sequence of alternating festoons, sheep and denticles.

History of studies
The church is mentioned by Enrico Costa (1937). After Marisa Porcu's study on the architectural history of Sassari (1996), she is quoted by Aldo Sari in the volume dedicated to the archdiocese of Turritana (2003).

Bibliography
E. Costa, Sassari, Sassari, 1937;
A. Marcellino, The Miraculous Holy Christ of St. Apollinare of Sassari, 1946;
C. Maltese, Art in Sardinia from V to XVIII, Rome, 1962;
E. Costa, Pictorial Archive of the City of Sassari (Diplomatic, Heraldic, Epigraphic, Monumental, Artistic, Historical), edited by E. Espa, Sassari, 1976; F. Segni Pulvirenti - A. Sari, Late Gothic and Renaissance Architecture, series “History of art in Sardinia”, Nuoro, Ilisso, 1994, p. 276;
M. Porcu Gaias, Sassari. Architectural and urban history from its origins to the 17th century, Nuoro 1996;
A. Sari, The Church in the Archdiocese of Sassari, series “Churches and Sacred Art in Sardinia”, Sestu, Zonza, 2003.