The House takes its name from Habsburg Castle, a fortress built in the 1020s in present-day Switzerland, in the canton of Aargau, by Count Radbot of Klettgau, who chose to name 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. The House of Habsburg gathered dynastic momentum through the 11th, 12th, and 13th centuries.
By 1276, Count Radbot's seventh generation descendant Rudolph of Habsburg moved the family's power base from Habsburg Castle to the Duchy of Austria. Rudolph became King of Germany in 1273, and the dynasty of the House of Habsburg was truly entrenched in 1276 when Rudolph became ruler of Austria, which the Habsburgs ruled until 1918.
A series of dynastic marriages enabled the family to vastly expand its domains to include Burgundy, Spain and its colonial empire, Bohemia, Hungary, and other territories. In the 16th century, the family separated into the senior Habsburg Spain and the junior Habsburg Monarchy branches, who settled their mutual claims in the Oñate treaty.
The House of Habsburg became extinct in the 18th century. The senior Spanish branch ended upon the death of Charles II of Spain in 1700 and was replaced by the House of Bourbon. The remaining Austrian branch became extinct in the male line in 1740 with the death of Holy Roman Emperor Charles VI, and completely in 1780 with the death of his eldest daughter Maria Theresa of Austria. It was succeeded by the Vaudémont branch of the House of Lorraine, descendants of Maria Theresa's marriage to Francis III, Duke of Lorraine. The new successor house styled itself formally as the House of Habsburg-Lorraine (German: Habsburg-Lothringen), and because it was often confusingly still referred to as the House of Habsburg, historians use the unofficial appellation of the Habsburg Monarchy for the countries and provinces that were ruled by the junior Austrian branch of the House of Habsburg between 1521 and 1780 and then by the successor branch of Habsburg-Lorraine until 1918.
Their principal roles (including the roles of their cadet branches) were as follows:
Numerous other titles were attached to the crowns listed above.
The progenitor of the House of Habsburg may have been Guntram the Rich, a count in the Breisgau who lived in the 10th century, and forewith farther back as the early medieval Adalrich, Duke of Alsace, father of the Etichonids from which Habsburg derives. His grandson Radbot, Count of Habsburg founded the Habsburg Castle, after which the Habsburgs are named. The origins of the castle's name, located in what is now the Swiss canton of Aargau, are uncertain. There is disagreement on whether the name is derived from the High German Habichtsburg (hawk castle), or from the Middle High German word hab/hap meaning ford, as there is a river with a ford nearby. The first documented use of the name by the dynasty itself has been traced to the year 1108. The Habsburg Castle was the family seat in the 11th, 12th and 13th centuries.