The very particular Church of San Domenico in the square of the same name was built in lovely local Gothic style between the end of the 13th and the beginning of the 14th century; it is annexed to a pre-existing convent built in 1247. The church was built with blocks of pink and white stone, arranged on alternating horizontal rows, a decorative constructive style that recalls the Umbrian churches of St. Chiara in Assisi and Santa Prassede in Todi.
The church can be entered through two doors: a small one with a lunette on the main facade, and through another larger and more elegant door framed by arched cornices, which opens on the right side. The upper part of the simple façade is also decorated with a large rose window.
Inside, the church has a single nave with a large transept and houses some noteworthy artworks, including two frescoes by Giovanni Lanfrancora depicting the Triumph of St. Thomas Aquinas and the Madonna with Child and four Saints (St Ann, St Catherine of Siena, St Catherine of Alessandria and St Helen). Over the centuries, the church underwent numerous renovations, and some Baroque decorations were added between the seventeenth and eighteenth centuries; these were removed in the twentieth century during a renovation by the architect Ugo Tarchi.