From Grado one only needs to cross the lagoon and then follow the Natissa river for a few kilometres to come upon the neighbouring Aquileia by boat; one of the biggest cities of the Roman Empire, is a cultural wealth of extraordinary value, so much so that it has been recognised by UNESCO as a site of historical and archaeological heritage for humanity. Founded in 181 BC, Aquileia has seen the passing of Caesar's legions in the 1st century BC and Attila's hordes five centuries later. It was an important commercial centre along the "Amber Route" that connected Northern Europe to the Mediterranean but it also had an important religious and evangelization role. Of particular interest is the area of the old river port, the markets, the patrician houses, the forum and the Via Sacra, as well the archaeological museum and the Patriarchal Basilica which contains the largest mosaics of the Western world.