1. Brooklyn Bridge
When it opened in 1883, this was the longest suspension bridge in the world - 1,595 feet spanning the East River between Manhattan and Brooklyn. That's what to do in New York City if you want to understand the scale of 19th-century ambition. John A. Roebling designed it, but he died before construction even started. His son Washington took over, then got debilitating decompression sickness from working in the underwater caissons. His wife Emily Warren Roebling stepped in, learning engineering on the fly and supervising the project for over a decade. The whole thing took thirteen years. Walking across puts you 127 feet above the water, with the wooden pedestrian walkway running down the center, elevated above the car traffic. The Gothic arches of the towers are more dramatic up close than in photos. You see the whole sweep of lower Manhattan on one side, Brooklyn's waterfront on the other. It's one of those top sights in New York City that actually lives up to expectations - partly because you're moving through it, not just looking at it. The bridge is a National Historic Landmark now, but it's still just a working piece of infrastructure that happens to be beautiful.