Berlin's Unité d'Habitation is Le Corbusier's 1957 housing block near the Olympiastadion, built as part of the city's postwar architectural experiments. It is not a polished museum piece, but it is a useful real-world example of the ideas behind modern high-density residential design.
The building is mainly worth the detour for architecture travellers or anyone already out by the stadium. From the outside you can read the scale, rhythm, and colours that made the Unité model so influential and so argued over.