Starting in Mérida's historic centre by the Plaza Grande, 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 White City's grid. The tour is fully self-guided — no guide, no fixed start time, just your group and the city. The Plaza Grande sets the scene — laurel shade, confidenciales love seats and the Casa de Montejo's conquistador facade. Riddles settle into the kissing chairs. The Catedral de Mérida rises on the east side, built in the 1500s with stones from Maya temples — the oldest cathedral on the American mainland. Trivia reads the recycled walls. Then Santa Lucía Park offers arcades, sculpture and the little stage where Yucatecan serenades have played for centuries. Around two hours through pastel streets, marquesitas within reach. The leaderboard announces the winner — trova music optional but likely.