Cities Project Cities Project NPR's Series On Urban Life In The 21st Century

The broadcast tower at Alexanderplatz looms over the city center. A crossing point of tourists, commuters, shoppers, lovers, artists and bums, Alexanderplatz was rebuilt by the communist authorities of former East Germany in the 1960s. Today, it's a popular gathering place in the reunified city. Sean Gallup/Getty Images hide caption

itoggle caption Sean Gallup/Getty Images

Lebanon's parliament sits in Beirut's rebuilt Nejmeh Square, near the center of the city. Unlike many of Beirut's neighborhoods, the square is often mostly empty. Tim Fitzsimons/NPR hide caption

itoggle caption Tim Fitzsimons/NPR

Artists' renderings of New Meadowland show how the wetland would be designed for human recreational use as well as flood control. The berm shown would be a path through the park when water was low (left). When storms came in, the wetlands would flood, and the berm would protect local development. Courtesy of New Meadowlands hide caption

itoggle caption Courtesy of New Meadowlands

New York state is buying homes like this one in Staten Island's Fox Beach neighborhood as part of a Hurricane Sandy recovery project in the hopes that demolishing them will help nature return and provide a barrier to future storm surges. Matthew Schuerman/WNYC hide caption

itoggle caption Matthew Schuerman/WNYC

The Mathare Valley, shown here in an aerial map, is one of the largest and oldest slums in Nairobi, Kenya. Residents are using hand-held GPS devices to map the area, which comprises 13 villages and is home to nearly 200,000 people. Courtesy of Muungano Support Trust and Jason Corburn, UC Berkeley hide caption

itoggle caption Courtesy of Muungano Support Trust and Jason Corburn, UC Berkeley

Cable cars move commuters over a complex of shantytowns in Rio de Janeiro, one of many cities taking part in the smart city boom around the world. Felipe Dana/AP hide caption

itoggle caption Felipe Dana/AP