Starting at Campo Erberia, beside the Rialto markets, you'll open the Explorial app, enter the 6-digit game code that you received by text and Viator chat message, and join the flow of the floating city. The tour is fully self-guided — no guide, no fixed start time, just your group and the city. The Ponte di Rialto opens proceedings — the marble bridge that carried Venice's commerce for centuries. Riddles weigh gold, spices and gondola tolls. Piazza San Marco follows in full splendour: basilica domes, the Campanile and café orchestras. Trivia spans doges, pigeons and Napoleon's compliments. Then the hunt turns secretive at Casino Venier, one of the hidden gambling salons where masked Venetians misbehaved in style. Around two hours through the busiest and most beautiful square mile in Europe. The final leaderboard decides who truly knows La Serenissima.