Your starting point is Marktplatz in central Basel. Open the Explorial app, enter your 6-digit game code that you received by text and Viator chat message, select German or English, and tap Start. The trail takes you across both sides of the Rhine, with the Wettsteinbrücke as the connecting thread. The Rathaus — Basel's spectacularly red-painted Gothic town hall — features early with a riddle about the painted facade details rather than the standard postcard shot. The Bürgerliches Waisenhaus Basel, the ornate baroque building that served as the city's civic orphanage for three centuries, brings an observation task about its history and role in the city. The Wettsteinbrücke features in a photo challenge that makes use of the Rhine views in both directions. The streets are compact and easy to navigate on foot. Groups tend to get drawn into the historical riddles more than expected — Basel has a surprisingly rich backstory. The app shows the final ranking when the last task is done. Kleinbasel gets fewer visitors than the museum quarter across the river; the trail makes a case for crossing over.