Salzburg (, ; literally "Salt-Castle"; ) is the fourth-largest city in Austria. In 2020, it had a population of 156,872. The town is on the site of the Roman settlement of Iuvavum. Salzburg was founded as an episcopal see in 696 and became a seat of the archbishop in 798. Its main sources of income were salt extraction, trade, and gold mining. The fortress of Hohensalzburg, one of the largest medieval fortresses in Europe, dates from the 11th century. In the 17th century, Salzburg became a center of the Counter-Reformation, with monasteries and numerous Baroque churches built. Salzburg's historic center (German: Altstadt) is renowned for its Baroque architecture and is one of the best-preserved city centers north of the Alps. The historic center was enlisted as a UNESCO World Heritage Site in 1996. The city has three universities and a large population of students. Tourists also visit Salzburg to tour the historic center and the scenic Alpine surroundings. History Antiquity to the High Middle Ages Traces of human settlements have been found in the area, dating to the Neolithic Age. The first settlements in Salzburg continuous with the present were apparently by the Celts around the 5th century BC. Around 15 BC the Roman Empire merged the settlements into one city. At this time, the city was called "Juvavum" and was awarded the status of a Roman municipium in 45 AD. Juvavum developed into an important town of the Roman province of Noricum. After the Norican frontier's collapse, Juvavum declined so sharply that by the late 7th century it nearly became a ruin. The Life of Saint Rupert credits the 8th-century saint with the city's rebirth. When Theodo of Bavaria asked Rupert to become bishop c. 700, Rupert reconnoitered the river for the site of his basilica. Rupert chose Juvavum, ordained priests, and annexed the manor of Piding. Rupert named the city "Salzburg". He travelled to evangelise among pagans. The name Salzburg means "Salt-Castle" (Latin: Salis Burgium). The name derives from the barges carrying salt on the River Salzach, which were subject to a toll in the 8th century as was customary for many communities and cities on European rivers. Hohensalzburg Fortress, the city's fortress, was built in 1077 by Archbishop Gebhard, who made it his residence. It was greatly expanded during the following centuries. Independence Independence from Bavaria was secured in the late 14th century. Salzburg was the seat