Paper Mystery Walk Outside the Pantheon, from a Real Case

You collect the mystery in person, on paper, from a tourist information kiosk on Via Giuseppe Zanardelli. That is the first thing that separates this from every app-based walk in the city: there is a physical envelope, and you work through it standing in the street. The case is built on a real crime. Solve the mystery and the last section tells you what actually happened, which is the part people talk about afterwards. The route stays outdoors from beginning to end. Nothing to book, no queue, no interior to be admitted to. It runs through Piazza Navona, then Piazza delle Coppelle, a small square most visitors never turn into, then Piazza di Sant'Ignazio, and finishes in front of the Pantheon in Piazza della Rotonda. Pause whenever you like. Nobody is waiting for you and the envelope does not expire at the end of the afternoon.