After the Carolingian Palatinate probably ended with a fire between 1017 and 1027 and the rulers of the Salians showed little interest in the city, the settlement activity only expanded again significantly with the active support of the Staufer in the 12th century. King Conrad III had a royal castle built on the Main in the middle of the 12th century with the Saalhof, which is still preserved in parts from this period . A little later, the urban area was enclosed with a wall named after the Swabian noble family, the course of which is still clearly visible in the shape of the city due to small remains above ground.