stone lined with Rhenish Schwemmstein (a traditional artificial material made of dried pumice and lime, similar to concrete), and stands at the eastern, Rhine valley end of the courtyard, over a vaulted cellar that Ernst Stahl dated to the time of Conrad of Hohenstaufen. It has a shingled hip roof 10 m high. Adjoining it on the southwest side is the so-called kitchen building, with Fachwerk first floor, which today is the residence of the hostel managers. On the courtyard side, a red sandstone tablet commemorates Duke Karl Ludwig's rebuilding of the castle. The inscription reads: CARL LVDWIG PFALTZGRAF CHVRFÜRST ERNEVERT MICH ANNO 1666 (Carl Ludwig, Count Palatine [and] Elector, remade me in the year 1666) Of the numerous details that Stahl once envisaged incorporating in the rebuilding of the castle, only the windows and chandeliers of the great hall exist today. The 11 windows of the hall, made of stained glass by the Düsseldorf glass painter Richard Gassen, depict the most important events in the history of the castle and the arms of the people or institutions of the Rhine Province in the 1920s. They are framed by versions in basalt which can only be seen from outside. The room has an oak plank floor and holds approximately 100 people. Bergfried Although documentary evidence leads to the conclusion that the castle was built in the 12th century at the latest, the archaeological investigations have been unable to provide proof. Stahl believed, however, that the preserved foundations of the bergfried (keep) should be dated to the 12th century. The keep is a round tower 7.5 m in diameter which stands on bedrock in the centre of the inner courtyard. It has walls 2 metres thick and is topped by a 16 m cone-shaped roof. The top floor, 4 m high, was added later, which can be seen from the different colour of the stone. Shield wall and main entrance The castle is defended from the high hillside on the west by a chemise wall which has been fortified to form a shield wall 2.6 m thick. There is an interior stairway, which does not, however, reach as far as the roofed chemin de ronde at the top of the wall; it is used to reach the upper floors of the 1930s tower building. Some of the tall, narrow embrasures were subsequently walled closed at the base and fitted with wooden