The Church of St. Sylvester in Tivoli dates to the late 12th century as the regularly walled stone structure attests.
Tradition holds that the church was founded by Pope Simplicius, along with the churches of St. Lawrence and St. Mary Major also in Tivoli. However, the construction, with its obvious Romanesque imprint, should be ascribed to a later date, such as the 12th century, when the area between the main thoroughfare, the present Via del Colle, and Piazza del Duomo, began to spread, following the expansion of the city walls in 1155.
The church is often compared to the Tiburtine Church of St. Peter, which dates back to the same era, because of the similarity of floor plans (nave and two aisles ending in a semicircular apse), stone walling and simple façade with pitched roof and marble framed central portal.
The building does, however, show signs of the remodelling that took place between the end of the 17th century and start of the 18th century when the needs of urban development caused the reduction of the church to a single chamber. At the same time, the twelve columns that separated the nave from the aisles were sold to Cardinal Alessandro Albani and the Romanesque bell tower was destroyed, leaving today a bell-gable.
The church has a flat wall façade with central portal and three narrow lancet windows in the higher part, crowned with a triangular tympanum with dentilled cornicing. The bell-gable is situated to the left of the façade, with a shrine to the Virgin set into its wall. The church leans against a private residence on the right.
Inside, the nave ends in a semi-circular apse, the walls are marked with arches and hold long, narrow lancet windows in the upper part. The presbytery is raised over steps that hide the crypt below. The ceiling is made of wooden trusses.