The sanctuary is sequestered by a 17th century marble balustrade either side of the free-standing high altar. The altar itself faces down the church, and has two storeys. The lower, 17th century, has simple polychrome marble panelling around an ovoid fenestra aperture looking into a little shaft connecting with the shrine of the martyrs in the confessio below. The upper part is modern, in grey-streaked white marble with a red cross.