Museum of Modern Art, Rio de Janeiro

Stepping onto this pedestrian footbridge brings you straight into one of Rio de Janeiro's boldest urban experiments. When architect Affonso Eduardo Reidy designed Flamengo Park in the 1950s, he faced an awkward dilemma. The newly reclaimed land sat right on Guanabara Bay, but between the historic streets of downtown and the park ran a rushing river of multi-lane car traffic. If people could not cross safely on foot, this vast green waterfront would belong entirely to automobiles.

Reidy's answer was this concrete overpass, calculated with engineer Sidney Martins Gomes dos Santos and opened in the 1960s. Instead of building a utilitarian steel cage, they stretched a long, gentle concrete ramp high above the roaring asphalt. The walkway takes its name from Paulo Bittencourt, the director of the influential newspaper Correio da Manhã and the late husband of Niomar Moniz Sodré, the relentless patron who fought political battles to get the museum built.

As you walk along it, the bridge behaves almost like a camera lens. Downtown Rio gradually drops behind you, and the long, low concrete frame of the museum opens up directly ahead, anchored against the bay and Sugarloaf Mountain. Reidy wanted the approach to feel deliberate: you leave the noise of the commercial center behind, rise above the speed of modern traffic, and step down into a landscape made entirely for leisure and modern art.