Built in 980 but destroyed during the conflict between the Guelphs and the Ghibellines in 1028, it was rebuilt only in 1256 when the body of San Firmano, the patron saint of the town, was found.
Essentially Romanesque, one enters the main portal decorated with a Byzantine lunette with five figures in high-relief made out of a Roman statue which is still visible on the inside of the church. Facing East, the basilica has three naves terminating in circular apses with twelve pilasters which support the rounded arches. The high staircase is characteristic with 17 steps leading to the presbytery where one can admire a lunette portraying the Madonna upon throne with Child between Saint Firmano and Saint Sebastian, a fresco by Giacomo di Nicola from Recanati of 1456.
On the altar of the crypt, there is a statue of Saint Firmano of the Marchigiano School in multi-coloured terracotta dating back to the 15th century. At the feet of the statue, the relics of the Saint have been placed. The altar is supported by an arch and, according to tradition, if you pass under it from seven to nine times in a row, you will be freed of any bone aches. 1256