Hohenstaufen castle was built about 1070 by Frederick I of Hohenstaufen—even before he became Duke of Swabia, as a fortress to protect family interests in the vicinity. Until the 13th century, the castle was a possession of the imperial and royal family, the Hohenstaufen dynasty. In 1181, Emperor Frederick Barbarossa stayed there; in 1208, Irene Angelina, the widow of Barbarossa’s son, the recently murdered Philip of Swabia, died at Hohenstaufen Castle.
Since the German unification of 1871, Hohenstaufen Castle has been regarded as a national monument. The archaeologist Walther Veeck undertook excavations on it between 1936 and 1938, and further excavations were made between 1967 and 1971, uncovering and securing the castle foundations. A Hohenstaufen memorial stele (Stauferstele) was inaugurated in 2002. In 2009 additional work was done to preserve the site. – Wiki