"Facing an open piazza and cradled between a well-turned campanile (1178) and a haphazard but apparently habitable ancient tower (fourteenth century), its tufa faŤade asserts a sharp geometry with a quietly stated verticality. Note that it is subdivided by narrow pilasters—a line of tiny arches in between—and given accents by the large rose window and the projecting, trimly arched porch. The north wall, on the other hand, stresses the horizontal—such dichotomy in the Middle Ages was not uncommon—its alternating bands of light and dark stone finding a congenial echo in the campanile. This Romanesque church is the fifth on the site, earlier ones having been destroyed by fire or man or having been outgrown. Part of the present interior dates from a fourteenth-century expansion, when a colorful Gothic keel-shaped ceiling of painted wood was installed."

— G. E. Kidder Smith. Looking at Architecture. p48.