The Porta San Lorenzo (from close to a medieval church dedicated to the saint and remembered in medieval sources at the beginning of the fourteenth century.) Is located on the Via Latina in the eastern sector of the urban area of Aquinum. It is a door to a rectangular shaft preserved almost entirely built of square blocks of local travertine. The base is decorated on the facades, and for a short distance along the short sides, from a socket molded with profile groove descending. The entrance arches, east and west, are all in the sixth with a single ring segments and an aperture of 3.60 m. On the western side, on the sides of the arch, there are two rectangular receipts, for the housing of decorative elements.