Starting at Plaza de la Almoina, beside the ornate Casa Punto de Gancho, you'll open the Explorial app, enter the 6-digit game code that you received by text and Viator chat message, and begin where Valencia itself began. The tour is fully self-guided — no guide, no fixed start time, just your group and the city. La Catedral de Valencia rises next door, guarding what many believe is the true Holy Grail. Riddles weigh the evidence, chapel by chapel. The Torres de Serranos follow — the massive 14th-century gate that survived the walls' demolition to become the city's triumphal front door. Trivia mans the battlements. Back at the Plaza de la Almoina, glass floors reveal Roman baths and streets beneath your feet, with clues buried in every layer. Around two hours through the Ciutat Vella, horchata breaks permitted. The leaderboard crowns the winner beneath the Miguelete.