The cathedral interior consists of a single-aisled nave with four chapels to each side. The nave is covered by an open wooden A-framed roof divided into four bays by lesene of yellow marble. The chapels are roofed by barrel vaulting and lit by high single windows; they are connected by high round arches. The fourth chapel on the south side, which is deeper than the others, has on its back wall a marble altar dedicated to the Virgin Mary surmounted by a wooden polychrome statue of the Madonna and Child.
