Chicago, USA

Chicago is the birthplace of the skyscraper, home to the 1884 Home Insurance Building—the world's first steel-frame skyscraper—and 3 of the tallest buildings in the Western Hemisphere, including the 1,451-foot Willis Tower. The city's Architecture Foundation runs the largest boat tour in North America, attracting 1.2 million visitors annually, who view 130 skyscrapers designed by legends like Louis Sullivan and Mies van der Rohe. This structural innovation legacy, driven by the 1871 fire that cleared 18,000 buildings, makes Chicago 60% more walkable for architecture enthusiasts than the average American city.