Turquoise Trail Walking Tour Explore Tucson’s rich history with the Turquoise Trail app—your guide to a self-paced walking tour through the heart of Downtown Tucson. This 2.5-mile loop highlights Spanish Colonial architecture and some of the city's most historic landmarks. The route is marked by a distinctive turquoise line painted on the sidewalk. For just $5, the GPS-enabled audio tour is available for purchase in the app. The trail begins at the Tucson Presidio Museum, located at the northeast corner of the original Presidio San Agustín del Tucsón, founded in 1775. The app also includes a tour of the museum, featuring a reconstruction of a corner of the fort, an 1860s Sonoran Row House, and a 2,000-year-old Indigenous pithouse.