Segusium
The city, cited in the itineraries, is mentioned by Strabo (4.1.6), Pliny (3.17), Suetonius (Ner. 18), and Ptolemy (3.1.40); and recorded by Ammianus Marcellinus, Cassiodorus, and Nazario in the Panegyric to Constantine. It is situated in the foothills of the Alps where roads lead through the Alpine passes of Monginevro and Moncenisio to the valleys of the Durance and of the Arc. A Celto-Ligurian oppidum of the Segusians, the city came under Roman rule in the Augustan age, and under Nero became a municipium at the time the province Alpium Cottiarum was instituted. Segusium was fortified during the Late Empire, and witnessed the siege of Constantine during the contest with Maxentius in A.D. 312.
The city plan shows characteristics of spontaneous formation, radiating from the primitive nucleus which excavation has localized near the present Porta Castello. At the intersection of the major roads in the forum indeterminate remains of important buildings have been found, including remnants of statues and a large votive base. From there the Gallic road continues toward the S and arrives at the summit of the hill, where there are ruins of ancient structures, perhaps large homes or public buildings. There is also an Arch of Augustus, with a single arch between pilasters and Corinthian columns at the corners. It bears an inscription and a figured frieze commemorating the friendship pact concluded with Rome in 9 B.C. by Julius Cozius, king of the Segusians and of the 14 cities of the Cottian Alps.
Little is known of the city in the early centuries of the Empire. Remains of roads and buildings furnish fragmentary and uncertain dates, except for clues from the presence of a bath building in the area of the present theater.
The only public building of which significant remnants have been found is the amphitheater, erected on the edge of the inhabited area in the SW section of the city. Using the fan-like formation of the hillside, it is in part supported by the terrain. The axes of the arena (33 x 44 m) are almost circular in shape, and the podium which delimits it is 3 m high. The cavea has an annular substructure with stone tiers, and a rostrum at the center of the S side. Of the three entrances to the arena, one leads to the extremity of the lesser axis on the side toward the valley. On this side the monument was adjacent to the shoulder of a paved road, perhaps the Via Gallia itself, at the point in which, from the bottom of the valley flanking the necropolis, it rose toward the W. Constructed in the 2d c. on the remains of an earlier building, the amphitheater indicates how far out of town the suburbs extended in the early centuries of the Empire. To the N and to the E the position of the necropoleis along the roads leading from Torino furnishes equally significant information about the city's development.
The city walls probably were not constructed before the second half of the 3d c. A.D., when the W strip of the city was excluded, perhaps for reasons of security. The perimeter, of which the entire course is known though sometimes partially preserved and sometimes greatly altered or indicated only by the alignment of the roads, extends for ca. 1250 m and encloses an area of almost 5 ha. The preserved stretches, in dry masonry faced in opus incertum, have a maximum preserved height of about 6 m, a width of 3 m, and jutting circular towers.
Of the two main gates to the city, opening at the extremities of the principal E-W axis, there remains today the W gate called the Porta Savoia. Its two circular towers, each 5 m in diameter, are joined by a span. Its single arch was altered in the 17th c.
A third gate opens at a projection of the wall at the W extremity of the mediaeval castle on the summit of the hill. It has a single arch, with a blind span between two circular towers. On the inside is a courtyard (7 x 6 m), perhaps covered, from which rooms opened. Not far from the gate two arches span the road. They are faced with reused squared blocks with stone chips filling the cracks. It is believed that the remains, subsequently inserted into the defensive system against which they rest in the SW corner, belonged originally to the aqueduct feeding the Baths of Gratianus, which were noted in an inscription (CIL V, 7250), now lost.
The material found in the excavations is housed in the local Museo Civico, in the Museo del Seminario, and in the Museo di Antichità at Torino.
BIBLIOGRAPHYA. Taramelli, “Note archeologiche segusine,” NSc (1898) 263ff; E. Ferrero, L'arc d'Auguste à Suse (1901); F. Studniczka, “Uber den Augustusbogen in Susa,” Jahrbuch des Kaeserlich Deutschen Archaeologischen Instituts (1903); P. Barocelli, “Segusio,” Boll. Soc. Piem. Arch. (1929) 62ff; id., “Susa-Anfiteatro,” NSc (1932) 3; id., “Appunti di topografia segusina,” BMusImp 7 (1936) 3ff; C. Carducci, “Scavi nel Castello di Adelaide in Susa,” NSc (1938) 328ff; id., “Scavi nella area del Castrum,” NSc (1941) 20ff; id., Guida di Susa (1961); id., “Problemi urbanistici e artistici dell'antica Segusio,” Atti I Congr. Int. Arch. Italia Sett. (1961, 1963) 129ff; id., Arte romana in Piemonte (1968) 26ff; B. M. Felletti May, “Il fregio commemorativo dell'arco di Susa,” Rendiconti Pontif. Accad. Arch. (1961) 129ff; S. Finocchi, “Susa-Anfiteatro romano,” BdA (1964) 389ff; J. Prieur, La province romaine des Alpes Cottiennes (1968).
Strab. 4.1.6; Plin. 3.17.123; Ptol. 3.1.40; Amm. Marc. 15.10.3, 7; Tab. Peut.; Rav. Cosm. 4.30.249.
S. FINOCCHI