I shall now allow myself a slight license, in the form of an excursion outside of Umbria toward the south.
A visit to Aquino, the ancient Aquinum, in the northern part of Campania, rounds out one’s conceptions of the architecture that ushers in the Augustan age, and joins the monuments of Umbria that we have been studying, to the Augustan works in Northern Italy and Dalmatia that are described later.
Aquinum stood at the junction of the ancient Via Latina with the road to Minturnae and the coast. It was originally a city of a type similar to the neighboring Latin and Volscian cities to the north. It then became an allied municipality and finally, in 41 B.C., it received a colony sent by the triumvirs. Marc Antony stopped here on his way south at this time, and it was prominent both as a city and fortress.
The site has scarcely been touched. A number of ruins are standing in plowed fields, as modern Aquino does not occupy exactly the area of the old city. There are the foundations of two temples, a theater and amphitheater and a number of tombs. It would be quite well worth excavating, for Aquinum was considered a not unimportant city in the age of Strabo and from its position must have partaken of the art both of Campania and Rome.
Quite a stretch of city-wall, in courses of regular travertine blocks, joins to so-called Porta S. Lorenzo which stands, in excellent preservation, across the modern road. It is a plain, impressive gate, but its value is even more historic than aesthetic. Delbrück calls it a “double gate of Servian type,” which would imply an early date, preceding the Roman colony. With this inference I cannot agree, because its masonry is of a type common under the triumvirs. Even as late in the reign of Augustus as 6 B.C., the gates of Saepinum show the same treatment of voussoirs. At the same time its type is very archaic and interesting as giving us a model for reconstructing the pre-Augustan gates of Rome.
In both plan and vaulting this gate is unique for its age. It is almost square, with heavy walls and superstructure, the only surviving example of the Janus gates such as were used in Rome under the Kings and the Republic. The arched gate at Ferentino, much less well-preserved, and which I have already described, gives an earlier form of this type, when the passageway was still uncovered. Similar open-court gates occur at Cosa and Volterra in Republican times. Here at Aquino the gate, though almost square, was not a Janus Quadrifrons, because it had but one passageway. It looked at first as if it were a free-standing structure, as there seemed to be no breaks in the stonework, but I found that the city wall joined the corner of the gate. A slight excavation would be needed to determine the extent and period of the connection.
The fact that the passageway leading through the core of the gate into the city is vaulted is most interesting. It has a massive cross-vaulting, 5.15 met. square, which springs from four piers surmounted by plain plinths above which a heavy ledge runs across the two façades, behind the voussoirs of the arch, helping to form the square plan for the vault.
The corner piers furnish narrow transverse arches and support the arêtes or ridges of the vaulting. I have enlarged upon this construction because it is of especial importance for the history of vaulting. Rivoira’s epoch-making publication on the Roman origins of Byzantine and medieval architecture, has brought this question again to the front, and I venture to assert that this gate at Aquino is the earliest remaining instance of the cross-vault, the prototype of those in the Janus arches of the Forum Boarium in Rome and of Saxa Rubra near Rome, built three or four centuries later!
At some distance beyond this gate is a beautiful arch which the common people have long insisted on calling Marc Antony’s arch, “l’arco del re Marc Antonio.” It is near the church of S. Maria Ottolina, on the edge of a field, and through its archway races a watercourse that runs a near-by mill. The artificial dykes of the water-course conceal the lower half of the arch and dwarf its proportions, but nothing can obscure its charm. Though built of a fine-grained travertine it gives an impression of almost as great delicacy and refinement as if it were of marble. We instinctively bracket it with the Hellenistic temples of Rome, Cori and Palestrina, and this impression is strengthened by the use of the Ionic order with the Corinthian. Its position across the ancient highway outside the walls, its isolation and its form, combine to show that it is the Colony arch of Aquinum, built on the pomerium line of the new colony in about 41 B.C. If so it is the earliest extant of the so-called triumphal arches.
It is a strange fate that now sets it across a watercourse, which is gradually undermining its foundations. Its keystone has sagged,’ and this most charming and earliest of arches is in danger of collapse for the want of a very small sum. The upper structure has disappeared. The general order inclosing the arch is Corinthian, with corner shafts engaged in the masonry. But the minor order of shafts supporting the arcade is Ionicthe only use of this order with which I am acquainted in the field of memorial arches. It is, probably, due to Southern influence. Other pre-Augustan and early Augustan works either use the Corinthian or the Doric, or combine these twoa sign of Italic influence.
The extreme slenderness of the arch is a characteristic. It has no core, but is built throughout of wonderfully jointed blocks laid without cement. Of attic, cornice, architrave, frieze there is no trace. I seemed to recognize blocks from these missing parts in the walls of the adjoining mill and in the neighboring medieval church, where there were built in numerous decorative architectural members of antique workmanship. The famous Renaissance architects of the San Gallo family admired and drew this arch, and I find that in their time, at the close of the fifteenth century, it still had a two-stepped architrave resting on the Corinthian shafts, and was even then used for the watercourse!