Aquileia was built as a military bridgehead for what would become the Roman conquest of the areas of the Danube. The city was transformed into an important trading hub thanks to the Natisone – Torre river which goes through it and to the road network connecting it with the Po Valley and the rest of Europe. At the end of the empire, it was the fourth largest Roman city in Italy and the ninth in the entire empire. The basilica of Aquileia is considered the Ecclesia Master for the whole of Western Europe, because the new faith radiated from these lands. The Archaeological Museum, Roman Forum, Necropolis and Mausoleum are among Aquileia’s most important remains.