One building holds a forest of arches and a cathedral inside a mosque — and that's just the first stop. This app-led scavenger hunt takes you through Córdoba on foot, using phone-based riddles to guide you from one landmark to the next. No guide, no fixed start time. • Circle the Mezquita-Catedral, the world's most famous architectural plot twist • Patrol the gardens of the Alcázar de los Reyes Cristianos • Pass through the Puerta del...