Located in the central Repubblica Square, the collegiate church was founded around the year 1000. Its current Latin-cross layout was implemented in the years from 1743 to 1770 with shapes derived from Vanvitelli’s architecture.

There are many praiseworthy works inside: a “Last Supper” by Felice Pellegrini (1594), a 16th century Tuscan art statue of Saint Thomas, Saints Stephen and Victor with the Madonna by the Dutchman Ernst de Schaych (1567- 1631) who lived in Castelfidardo and the surrounding area for more than a decade, contributing to the spread of Nordic painting elements in the figurative Marche culture.