TREPONTIUM or TRIPUNTIUM, a place on the Appian Way near the entrance of the Pontine Marshes, 4 miles nearer Rome than Forum Appii. It is not mentioned as a station in the Itineraries, but we learn from an inscription of the time of Trajan that it was from thence the part of the road which was restored by that emperor began. This important work, as we are informed by another inscription, was continued for nineteen miles,a circumstance that explains the origin of the name of DECENNOVIUM,which occurs at a later period in connection with the Pontine Marshes. Procopius calls the Decennovium a river;but it is evident that it was in reality an artificial cut or canal, such as must always have accompanied the highroad through these marshes, and as we know already existed in the days of Horace from Forum Appii. The importance of this work will account for the circumstance that we find the Pontine Marshes themselves called by Cassiodorus Decennovii Paludes.(Cassiod. Var. 2.32, 33; Procop. B. G. 1.11.) The site of Trepontium is clearly marked at the distance of 39 miles from Rome, by the name of Torre di Treponti, together with the remains on the 3 ancient bridges, from which it derives its name (Chaupy, Maison d'Horace, vol. iii. pp. 387—392; D'Anville, Analyse de l'Italie, pp. 184—187.)
The inscriptions above cited are given by Sir R. Hoare, Class. Tour, vol. i. pp. 97, 98; and by the Abeé Chaupy (l. c.). The name of Τραπόντιον, found in Strabo (5. p. 237) among the cities on the left of the Appian Way, can hardly be other than a corruption of Trepontium, but it is wholly out of place in that passage, and is supposed by Kramer to be an interpolation.
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