Mars, Ara

This altar, the primary cult site of Mars in Rome, was one of the most important and ancient religious monuments in the *Campus Martius. Though the dedication of the plain itself to Mars was linked with the expulsion of the Tarquinii (Livy 2.5.2 ff.), the altar was thought to date from the time of king Numa (Festus 204: in Martis ara in Campo). During the Republic, the altar was closely associated with the activities of the censors (Livy 40.45.8; cf. Varro, Ling. 6.87), and thus was linked with the *Villa Publica, in which it probably stood. Some scholars have attempted to locate the Ara Martis in the N section of the campus, in the vicinity of the *Pantheum (Lanciani, Platner, Welin). This placement represents an attempt to reconcile its location with the descriptions of literary sources which may refer to a separate aedes of *Mars ‘in Campo’. More important is the evidence of Livy (35.10.12), who says that the altar was connected to the *Porta Fontinalis by means of a *Porticus Aemilia (Campus Martius) in 193 B.C. (Castagnoli). Various locations in the S Campus Martius have been suggested to account for the distance a mid-Republican portico might span. Hülsen thought it lay near the modern Piazza del Gesù, while Richardson identifies it with an unlabeled square structure depicted on the Severan Marble Plan (Rodríguez Almeida, Forma frag. 35a), as part of a villa Publica reconstituted by Domitian as the Divorum. The most attractive hypothesis to date is that of Coarelli, who focuses on a series of walls discovered under Via del Plebiscito in 1925. These he associates with a Hadrianic rebuilding of the altar, and from them reconstructs a grand peribolos enclosure, c. 65 x 65 m, inside which stood the altar on a massive raised platform. The excavation also revealed some traces of an earlier structure on this site (Mancini). These remains, if Coarelli’s identification holds, might give us some indication of the location and general magnitude of the Republican and Augustan Ara Martis.