Starting at the Triunfo de San Rafael monument by the Puerta del Puente, you'll open the Explorial app, enter the 6-digit game code that you received by text and Viator chat message, and step into the old city. The tour is fully self-guided — no guide, no fixed start time, just your group and the city. The Mezquita-Catedral commands the opening riddles — 850 candy-striped arches with a Renaissance cathedral grown improbably through the middle. Even Charles V had regrets, and trivia quotes him. The Alcázar de los Reyes Cristianos follows, fortress of kings and Inquisition headquarters, its gardens now all fountains and orange trees. Then back through the Puerta del Puente, the Renaissance gate framing the Roman bridge across the Guadalquivir. Around two hours through the flower-hung Judería. The final scores bloom on the leaderboard like a patio in May.