The House of Habsburg, also known as the House of Austria, was one of the most powerful dynasties in the history of Europe and European influenced polities. They were best known for ruling vast realms throughout Europe and the Americas during the Middle Ages and early modern period, including the Holy Roman Empire and Spain.
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, was elected King of the Romans.