Aquileia (äkwēlĕˈyä) [key], town, in Friuli–Venezia Giulia, NE Italy, near the Adriatic Sea. Founded in 181 B.C. by the Romans, it was a stronghold against the barbarians and a trade center. Later, the town was destroyed several times by invaders, notably by Attila (A.D. 452). In the 6th cent. Aquileia became the see of a patriarch. Fleeing the Lombards in 568, the patriarch took refuge in Grado, the island port of Aquileia, and remained there while Aquileia elected its own patriarch. The pope recognized (7th cent.) both patriarchates; in 1445 that of Grado was transferred to Venice. From the 11th cent. Aquileia flourished under the temporal rule of its patriarchs, who acquired Friuli, Carniola, and Istria. Decline began in the 14th cent., and in 1420 Venice occupied Aquileia and Friuli. Aquileia was under Austrian rule from 1509 to 1918, when it passed to Italy. The patriarchate was abolished in 1751. Of particular note is the Romanesque basilica (11th cent., partly restored in the 14th cent.), with a well-preserved mosaic floor and frescoes of the 12th and 13th cent. There are also Roman ruins and an archaeological museum.