This arch is set astride Via di Mercurio, of which it marks the beginning, in front of the Forum Bath and the Temple of Fortuna Augusta, near the intersection where Via delle Terme, Via della Fortuna, Via del Foro and Via di Mercurio cross. This is an honorary arch in brick with a single passage-way and its attribution to Caligula is based on an equestrian statue in bronze, found in fragments, which must have originally been set on the attic and which has been identified as Caligula. The arch was built on the same axis as the arch attributed to Tiberius or Germanicus, which constitutes a monumental entrance to the Civil Forum, and which was also topped by an equestrian statue.