Karl Marx-Hof

Heiligenstadt, Vienna

Built between 1927 and 1930 by city planner Karl Ehn, it held 1,382 apartments and was designed for the population of about 5,000. At over one kilometre in length (1100m, 0.68 mile) and spanning four tram stops, Karl Marx-Hof holds the distinction of being the longest single residential building in the world.

Photo by Lord K