After almost 40 years on the throne, he will be succeeded by his son Prince Felipe.
Spaniards marched to protest deep austerity, corruption & the privatisation of public services.
Spain's opposition Socialists have told Prime Minister Mariano Rajoy to resign.
Spanish Prime Minister Mariano Rajoy wants to know what conditions will be attached to an EU bailout.
Financial markets responded with relief to Saturday's euro zone deal to lend Madrid money.