House of Valois-Burgundy
Having inherited his father's possessions in 1506, he was already a powerful ruler with extensive domains. On Maximilian's death these domains became vast. He was now ruler of three of Europe's leading dynasties—the House of Habsburg of the Habsburg Monarchy; the House of Valois-Burgundy of the Burgundian Netherlands; and the House of Trastámara of the Crowns of Castile and Aragon. This made him ruler over extensive lands in Central, Western, and Southern Europe; and the Spanish colonies in the Americas and Asia. As the first king to rule Castile, León, and Aragon simultaneously in his own right, he became the first King of Spain. His empire spanned nearly four million square kilometers across Europe, the Far East, and the Americas.