the northern ring wall was a longish building with a stone residential building attached to its northern end. Its ground floor was divided into several small rooms, and at the south end there was a timber-framed building whose outside wall was the southern defensive wall. Two more timber-framed buildings stood on the west side in the shelter of a shield wall which protected the castle on the side where the hillside is higher. The buildings thus enclosed a long, narrow inner courtyard, in the centre of which was a round Romanesque keep (bergfried), with an outside wall 4 m thick. Water was supplied to the castle by a well sunk into the hillside within the shield wall. It was connected by a tunnel at a depth of approximately four metres to the moat outside the walls. Finds of fragments of early Gothic vaulting and of a Gothic window showed that the castle had a chapel. Until then, the only evidence had been a mention in the 1471 testament of Ruprecht of the Palatinate, Archbishop of Cologne. It is impossible to know exactly where the chapel was, but it is presumed to have been on the first floor of the palas, where Merian's engraving shows a small bay window on the Rhine side of the building. In addition to the still existing artillery platform on the southwest side, there was a bastion in the northeast. Today The castle today is a 20th-century reconstruction, primarily based on the results of excavation and the 1646 engraving by Matthäus Merian. The rebuilding plans were mostly the work of Ernst Stahl, who closely followed Merian's depiction and used other historical models where the engraving gave no information. For example, the almost rectangular shape of the castle, measuring approximately 55 by 24 m, shows the typical regular layout and clear divisions of a castle of the Hohenstaufen period. The size of the modern buildings approximates that of those in the original castle; the oldest portions are the foundations of the keep, parts of the cellar under the palas and sections of the curtain wall. Since the castle is used as a hostel, it is not available for tours. However, the courtyard is accessible to the public and offers a fine view of the Rhine, since on that side there is only a low parapet. Palas The palas (residential building) is 2 storeys high, built of crushed