Isabel la Católica, or Isabella I of Castile, was a significant monarch in Spanish history, reigning from 1474 to 1504. She is best known for uniting the kingdoms of Castile and Aragon through her marriage to Ferdinand II of Aragon. Together, they completed the Reconquista by conquering the last Muslim stronghold in Spain, Granada, in 1492. Isabel's reign marked the beginning of Spain's rise as a global power. She sponsored Christopher Columbus's voyage in 1492, leading to the discovery of the Americas. Her policies also included the establishment of the Spanish Inquisition, aimed at maintaining Catholic orthodoxy in her realms.