Starting at the Jardim da Cordoaria, you'll open the Explorial app, enter the 6-digit game code that you received by text and Viator chat message, and set off into Porto's granite heart. The tour is fully self-guided — no guide, no fixed start time, just your group and the city. The Torre dos Clérigos points the way first — 75 metres of baroque bell tower, long the first thing sailors saw of home. Riddles count the steps so you don't have to. At São Bento station, twenty thousand azulejo tiles turn a train hall into a history book. Trivia picks out battles, coronations and everyday river life in blue and white. Then the Livraria Lello dazzles from its neo-Gothic facade — the crimson staircase inside inspired generations of writers and one very famous wizarding world. Around two hours of hills and marvels. Port wine across the river makes a fine trophy ceremony.