The title "Queen of Castile" refers to the female monarchs who ruled the historic region of Castile in Spain. Notable queens include Isabella I of Castile, who reigned from 1474 to 1504 and is famous for her role in the unification of Spain and the sponsorship of Christopher Columbus's 1492 voyage. The Kingdom of Castile was one of the most powerful kingdoms in medieval Spain, playing a crucial role in the Reconquista, the centuries-long effort to reclaim the Iberian Peninsula from Muslim rule. The queens of Castile often wielded significant political influence, shaping the course of Spanish history.