At that time, people lived in the "Hermitage", a small natural cave next to the current highway. In the year 45 BC, a few kilometres further west, the settlement Augusta Raurica was founded, the first Roman town in Switzerland, near modern Kaiseraugst. In the plains at Rheinfelden was then a large estate. Towards the end of the 4th century a border fort was constructed at the western settlement. Rheinfelden is first mentioned about 851 as Rifelt and in the first half of the 12th century it was called Rinfelden. In the second half of the 10th century, the entire Fricktal area—the Frick valley, a finger of land in northwestern Switzerland east of present-day Basel, between the Jura Mountains to the south, and the High Rhine border with present-day Germany to the north—was within Kingdom of Burgundy. At that time, Rheinfelden was granted to the von Wetterau family. They later adopted the title of Count of Rheinfelden. The Rheinfeldens built a fortress, "Stein", on the strategically located island; a riverbank settlement stood at the "Altenburg". The last of this comital line was Rudolf of Rheinfelden, Duke of Swabia (1057–79) and German antiking (1077–80) during the Investiture Controversy. When Rudolf died on October 15, 1080, in Merseburg, his territories were inherited by Berthold II of Zähringen.but the town went to his son Otto and his family the von Wetter's. Berhold's second son, Conrad, awarded market rights to the city, making it the oldest Zähringerstadt in Switzerland and the oldest city in the Aargau; in 1150 he also had the first bridge built across the Rhine, between Konstanz and Strasbourg. In 1218, Berthold V died without issue. In 1225, Rheinfelden gained Reichsfreiheit to become an Imperial City. A little over a century later, in 1330, the city pledged itself to the Habsburgs, becoming a part of Further Austria. In 1445, when the Habsburgs were fighting the Old Zürich War, insurgents destroyed the castle on the "Inseli", due to the city's allegiance with Basel. After a siege lasting several months, Rheinfelden was returned to Austrian subjugation in 1449. After the Waldshut War from 1468, all of Fricktal Burgundy pledged to the Habsburgs. After the Burgundians were beaten by the Old Swiss Confederacy in the Burgundian Wars, Rheinfelden land, not Title, was restored to Austria in 1477. During the 17th century, there was very little time during which the city enjoyed peace. During the Rappenkrieg,