Spain's architectural and artistic heritage is one of the most important in the world. Where to begin?

Cathedrals, monasteries, castles, palaces… There's so much to see and enjoy. Would you like a few examples? The Alhambra in Granada, the Great Mosque in Cordoba, the Aqueduct in Segovia, Gaudí's Sagrada Familia Cathedral, the Altamira caves, Mudejar architecture….