TONGRES (in Flemish TONGEREN). – City and ancient diocese in Limburg (Belgium), on the banks of the Icker River, a tributary of the Meuse. It is the ancient Adnatura Tungrorum, capital of the Civitas Tungrorum in the Roman province of « Germania inferior ».
The diocese was established as early as the 3rd century, but the first known bishop is St. Servatius (344–84), Maastricht (v.). With the invasion of 406, the city lost its importance and came to be administered by representatives of the bishop of Liège. A serious fire damaged it in 1677.
The ancient Notre-Dame cathedral is in the Gothic style of the 13th century, erected over the earlier Romanesque church, of which the crypt and cloister of the 12th century survive; the latter was restored in the 14th century. The apse and the final part of the three naves with the chapels belong to the 14th–15th centuries; the transept dates from 1456; the portico, façade, and tall tower were built between 1444 and 1586. The brass Paschal candlestick is the work of J. J. De Dinant; remarkable is a Romanesque Crucifix from the beginning of the 12th century. The adjoining treasury preserves a 6th-century ivory representing St. Paul, with a list of the bishops of Liège from 840 to 956 on the reverse; originally this ivory formed part of a diptych containing on the right the figure of St. Peter, now preserved in the Cinquantenaire Museum in Brussels, but partly restored (J. Helbig, L'art mousou depuis l'introduction du christianisme jusqu'à la fin du XVIIIe siècle, Bruxelles 1906, p. 23; M. Laurent, Les inoires prégofiques conservés en Belgique, there 1912, pp. 6–7, fig. 2). There are also two Gospel books, one from the 9th century and the other from the 11th; and a triptych with the relic of the Holy Cross, dating from around 1170. Also noteworthy are the church of the Hospital of St. James (1660–62) and that of St. Catherine, erected in 1294 but restored together with the adjoining béguinage of 1257.
Pope Pius XI, by apostolic letter of 20 February 1931, raised the ancient Notre-Dame cathedral, erected in honor of the Blessed Virgin Mary, to the dignity of a minor basilica, « Causae nostrae laetitiæ » (AAS, 23 [1931], pp. 373–75).
Excavations carried out in 1912 at T. confirmed its Roman origin and showed that its walls of that period enclosed a larger area than the medieval walls. Important studies on T. and its monuments have been published in the Bulletin de la Société scientifique du Limbourg since 1906.