"The cathedral took over 500 years to complete and is one of Milan's must-see sights; I recommend the Milanoguida two-hour Cathedral Rooftop tour, which includes skip-the-line admission, rooftop access with amazing city views, a headset for guided commentary, and close-up sights of its roughly 3,500 statues, 135 spires, and five bronze doors. The Duomo is also featured on larger city walks (Take Walks' Best of Milan and Sandeman’s highlights tour), so it's easy to include even on a short visit." - Matthew Kepnes