Trèves (Ger. Trier), a city of Rhenish Prussia, lies on the right bank of the Moselle, in a valley between low vine-covered hills, 69 miles by rail SW. of Coblenz. The river is crossed here by an eight-arch bridge, 623 feet long, whose Roman piers date from 25 B.C. 'A quiet, old-fashioned town, Trèves,' Freeman says, 'has a body of Roman remains far more numerous and varied, if not individually more striking, than any other place north of the Alps can show.' These include the 'Porta Nigra,' 118 feet long, and 95 high, one probably of the five gates by which Trèves was entered in Constantine's time; the so-called Roman baths (more probably part of an imperial palace); and a basilica built of Roman brick by Constantine for a court of justice, but demolished in great measure to make room for an electoral palace in 1614. This, however, was removed, and the basilica fitted up for a Protestant church in 1856. Beyond the walls are the ruins of an amphitheatre that could seat 30,000 spectators; and 6 miles off is the 'Igelsäule' or 'Heidenturm,' a monumental column, 71 feet high, sculptured with bas-reliefs of the 2d century. The cathedral of SS. Peter and Helena is an interesting structure of various antiquity, but chiefly in the early German Romanesque style of the 11th century. The most famous of its relics is the seamless or 'Holy Coat,' which consists of 'connected fragmentary particles of material.' Said to have been brought to Trèves by the Empress Helena, it is first referred to in 1106 by an anonymous monk, and was not a source of revenue till 1512. It was visited by nearly two million pilgrims in 1891, the first time of exhibition since 1844. A 'Holy Coat' is also shown at Argenteuil and in nineteen other places. Connected with the cathedral by a cloister is the beautiful Liebfrauenkirche (1243); and there is a library of over 100,000 volumes and many MSS., among them the 'Codex Aureus' of the Gospels, presented to the abbey of St Maximin by Charlemagne's sister, Ada. A university, founded in 1472, was suppressed in 1798. The industries comprise manufactures of woollens, cottons, and linens, besides a brisk trade in corn, timber, and Moselle wine. Pop. (1871) 21,442; (1891) 36,162; (1895) 40,026.
Trèves, which claims to be 1300 years older than Rome, derives its name from the Treviri, a Gallic or, more probably, a Belgic people, who in Cæsar's time inhabited a large district between the Meuse and the Rhine. Their capital, Augusta Trevirorum, seems to have become a Roman colony in the reign of Augustus, and ultimately was the headquarters of the Roman commanders on the Rhine, and a frequent residence of the emperors, especially Constantine. Sacked by Attila in 451, it passed to the Franks in 463, to Lorraine in 843, to Germany in 870, and back to Lorraine in 895, and was finally united to Germany by the Emperor Henry I. The Archbishop of Trèves was, as chancellor of Burgundy, one of the Electors of the Empire, a right which originated in the 12th or 13th century, and which continued till the French Revolution. The last elector removed to Coblenz in 1786; and Trèves was the capital of the French department of Sarre from 1794 till 1814, since which time it has belonged to Prussia.
See German works by Haupt (1822), Leonardy (1871), Wilmowski (1874–76), Hettner (1880), Steinbach (1883), and Beissel (1888); also Freeman's Historical and Architectural Sketches (1876), and Clarke's Pilgrimage to the Holy Coat of Trèves (1892).