Starting at Plaza de la Constitución in the heart of Oviedo's old town, you'll open the Explorial app, enter the 6-digit game code that you received by text and Viator chat message, and let the riddles guide your route. The tour is fully self-guided — no guide, no fixed start time, just your group and the city. Your first landmark is the Catedral de Oviedo, a Gothic treasure at the centre of Asturian religious life. Its Cámara Santa holds a collection of medieval relics, and the riddles here will send you searching for the stories behind the stones. The route then winds through Campo de San Francisco, Oviedo's green heart. Bronze sculptures of beloved local characters dot the park, and the app will point you to the ones with the most interesting tales to tell. The final stop is the Teatro Campoamor, an elegant 19th-century theatre best known as the venue for the Princess of Asturias Awards. Its grand facade and storied past make for a fitting finish to the hunt. The tour takes around 2 hours from start to finish. Oviedo is the kind of city that rewards close attention — and this tour is built to bring that out.