When Did Spain Become a Unified Country?

No single date marks Spain's "birth." Key milestones:

• Prehistory–Middle Ages: Iberian, Celtic, Roman, Visigothic, Muslim (Al-Andalus) periods.
• 1469: Marriage of Isabella I of Castile and Ferdinand II of Aragon—union of crowns.
• 1492: Fall of Granada (end of Reconquista); Columbus voyage.
• 1516: Charles I (Charles V) inherits united crowns—first Habsburg king of "Spain."
• 1715: Nueva Planta decrees (Philip V) centralize administration—modern unitary state.

The term "España" gained currency in the 16th century. 1469 is the symbolic start; 1715 the administrative culmination.