KYFFHÄUSER, a double line of hills in Thuringia, Germany. The northern part looks steeply down upon the valley of the Goldene Aue, and is crowned by two ruined castles, Rothenburg (1440 ft.) on the west, and Kyffhausen (1542 ft.) on the east. The latter, built probably in the 10th century, was frequently the residence of the Hohenstaufen emperors, and was finally destroyed in the 16th century. The existing ruins are those of the Oberburg with its tower, and of the Unterburg with its chapel. The hill is surmounted by an imposing monument to the emperor William I., the equestrian statue of the emperor being 31 ft. high and the height of the whole 210 ft. This was erected in 1896. According to an old and popular legend, the emperor Frederick Barbarossa sits asleep beside a marble table in the interior of the mountain, surrounded by his knights, awaiting the destined day when he shall awaken and lead the united peoples of Germany against her enemies, and so inaugurate an era of unexampled glory. But G. Vogt has advanced cogent reasons (see Hist. Zeitschrift, xxvi. 131–187) for believing that the real hero of the legend is the other great Hohenstaufen emperor, Frederick II., not Frederick I. Around him gradually crystallized the hopes of the German peoples, and to him they looked for help in the hour of their sorest need. But this is not the only legend of a slumbering future deliverer which lives on in Germany. Similar hopes cling to the memory of Charlemagne, sleeping in a hill near Paderborn; to that of the Saxon hero Widukind, in a hill in Westphalia; to Siegfried, in the hill of Geroldseck; and to Henry I., in a hill near Goslar.
See Richter, Das deutsche Kyffhäusergebirge (Eisleben, 1876); Lemcke, Der deutsche Kaisertraum und der Kyffhäuser (Magdeburg, 1887); and Führer durch das Kyffhäusergebirge (Sangerhausen, 1891); Baltzer, Das Kyffhäusergebirge (Rudolstadt, 1882); A. Fulda, Die Kyffhäusersage (Sangerhausen, 1889); and Anemüller, Kyffhäuser und Rothenburg (Detmold, 1892).