The city's appearance today is predominantly shaped by the key role it played in Germany's history in the 20th century. Each of the national governments based in Berlin —the 1871 German Empire, the Weimar Republic, Nazi Germany, East Germany, and now the reunified Germany— initiated ambitious construction programs, each with its own distinctive character. Berlin was devastated by bombing raids during the Second World War and many of the old buildings that escaped the bombs were eradicated in the 1950s and 1960s in both West and East. Much of this destruction was initiated by municipal architecture programs to build new residential or business quarters and main roads. Berlin's unique recent history has left the city with an eclectic array of architecture and sights.
In the eastern part, many Plattenbauten can be found, reminders of Eastern Bloc ambitions to create complete residential areas with fixed ratios of shops, kindergartens and schools. Another difference between former east and west is in the design of little red and green men on pedestrian crossing lights (Ampelmännchen in German); the eastern versions received an opt-out during the standardization of road traffic signs after reunification. The eastern Ampelmännchen design is now used in the western part of the city as well.
