ARCH, TRIUMPHAL; an edifice erected by the Romans in various situations, but more especially at the entrances of their cities, in honour of victorious generals, and in later times of the emperors. These structures were originally built of brick, but afterwards of stone, or marble ; their form was that of a parallelopipedon, having one, and often three, arched apertures in the longer side, decorated with columns, sculpture, and other embellishments; the whole being surmounted with a heavy attic. When three arches were employed, they were situate so as to have one large one in the centre with a smaller one on each side of it.
Under the emperors, triumphal arches became very numerous, and were made of costly materials richly orna mented. The oldest of such structures remaining in Rome is that of Titus, enriched with sculptures representing the triumph of that emperor. Two other arches erected in honour of Trajan are still in existence, the one at Ancona, the other at Benevento ; the former is of white marble of chaste ornamentation, consisting in part of bronze statues ; the latter has several fine relievos, and is in a state of good preservation. The above are single-arched ; several, however,
were constructed of three arches, amongst the most remark able of which are those of Constantine and Septimius Severus; that of Constantine has been cleared of the soil which had accumulated to some height round its base, and is perhaps the most beautiful and complete of any at Rome, but manifests some discrepancies of parts, as it was built partially of old materials from an earlier monument of Trajan ; that of Severus is a noble structure, but is much more dilapidated ; it is sixty-one feet in height, seventy-one in length, and twenty-two in depth, the central archway is twenty-two feet wide, and thirty-six high, the side ones ten feet wide, and twenty-two feet high.
But few structures of this kind have been erected by the moderns ; amongst them, however, we may notice one triple arch of Bonaparte on the Place du Carrousel, and a much • finer one at Milan.