The elegant honey-coloured sandstone Gothic edifice was built from 1235 to 1365. It is often referred to as the "cathedral", because of a bishop who is said to have stayed here after the French Revolution, but who wasn't recognised by Rome. The legend of the saint is depicted on St Nicholas Porch signed by "Maestro Humbert". Inside are an organ case by the 18C Silbermann workshop and a 14C carved Crucifixion.