Aquileia is an ancient Roman city in what is now Italy, at the head of the Adriatic at the edge of the lagoons, about 10 km from the sea, on the river Natiso, the course of which has changed somewhat since Roman times. Today, the city is small, but it was large and prominent in Antiquity, and is one of the main archeological sites of Northern Italy.
The Cathedral of Aquileia is a flat-roofed basilica erected by Patriarch Poppo in 1031 on the site of an earlier church, and rebuilt about 1379 in the Gothic style by Patriarch Marquard of Randeck.
The ancient buildings of Aquileia served as stone quarries for centuries, and no edifices of the Roman period remain above ground. Excavations have revealed one street and the north-west angle of the town walls, while the National Archaeological Museum (one of the most important museums of Ancient Rome in the world) contains over 2,000 inscriptions, statues and other antiquities, as well as glasses of local production and a numismatics collection.
The site of Aquileia, believed to be the largest Roman city yet to be excavated, is inscribed on the UNESCO World Heritage List.
In the Monastero fraction is a 5th century Christian basilica, later a Benedictine monastery, which today houses the Paleo-Christian Museum.