The Spanish monarchy, referred to as the Crown of Spain (Corona de España) in the Spanish Constitution of 1978, is the office of the King or Queen of Spain.
The Heir Apparent of the Spanish Monarchy receives the titles Prince of Asturias, Prince of Gerona and Prince of Viana, Asturias being on behalf of kingdom of Castile and Leon, Gerona on behalf of kingdom of Aragon, and Viana, a disputed title, on behalf of kingdom of Navarre.
The History of the Spanish monarchy can be traced back to the end of the middle ages, specifically to the alliance between Isabella I of Castile and King Ferdinand II of Aragon, the Catholic Monarchs, Reyes Catolicos.