The name Kyffhäuser probably stems from cuffese meaning head or peak. The settlement of Tilleda at the northern rim was already mentioned at the beginning of the 9th century in the Breviarium Lulli as Dullide, an estate of Hersfeld Abbey. A Kaiserpfalz at Tilleda is attested by the 972 marriage certificate of Empress Theophanu. A first castle on the mountain above the settlement my have been erected by Emperor Henry IV during his conflict with the Saxons. His son Henry V inherited the quarrels and the castle was finally sligthed by the Saxon Duke (and later Emperor) Lothair of Supplinburg in 1119. Lothair himself started the reconstruction in his later years and the Reichsburg Kyffhausen was completed under Emperor Frederick Barbarossa.
According to legend, Barbarossa is not in fact dead, but sleeps in a hidden chamber underneath the Kyffhäuser mountain, sitting at a stone table. His beard has supposedly grown so long over the centuries that it grew through the table. As in the similar legend of King Arthur, Barbarossa supposedly awaits his country's hour of greatest need, when he will emerge once again from under the mountain. The presence of ravens circling the Kyffhäuser summit is said to be a sign of Barbarossa's continuing presence.
Today, the mountain area is a tourist site featuring a restored medieval castle from the 11th century. Atop the mountain is the Kyffhäuser Monument, built in 1896, which depicts German Emperor William I and Frederick Barbarossa.