The house takes its name from Habsburg Castle, a fortress built in the 1020s in present-day Switzerland by Radbot of Klettgau, who named his fortress Habsburg. His grandson Otto II was the first to take the fortress name as his own, adding "Count of Habsburg" to his title. In 1273, Count Radbot's seventh-generation descendant Rudolph of Habsburg was elected King of the Romans. Taking advantage of the extinction of the Babenbergs and of his victory over Ottokar II of Bohemia at the battle on the Marchfeld in 1278, he subsequently moved the family's power base to Vienna, where the Habsburgs ruled until 1918.