Even older than León's cathedral, the Real Basílica de San Isidoro provides a stunning Romanesque counterpoint to the former's Gothic strains. Fernando I and Doña Sancha founded the church in 1063 to house the remains of the saint, as well as the remains of themselves and 21 other early Leónese and Castilian monarchs. Sadly, Napoleon's troops sacked San Isidoro in the early 19th century, but there's still plenty to catch the eye.
The main basilica is a hotchpotch of styles, but the two main portals on the southern facade are pure Romanesque. Of particular note is the Puerta del Perdón, attributed to Maestro Mateo, the genius of the cathedral at Santiago de Compostela. The star vaulting above the extravagantly beautiful altar are especially worth lingering over.