Most World Heritage sites are palaces, cathedrals or ruins. Berlin got onto the list in 2008 with flats. The Berlin Modernism Housing Estates are six residential developments built between 1910 and 1933, among them the Hufeisensiedlung in Britz, shaped like a horseshoe around a pond, the Gartenstadt Falkenberg with its bright colours, the Weisse Stadt in Reinickendorf and the Siemensstadt estate. Architects such as Bruno Taut, Martin Wagner and Walter Gropius designed them to give ordinary working families light, air, green space and decent bathrooms at a time when many Berliners lived in dark, cramped tenement blocks around courtyards.
The point here in Kreuzberg is a city marker rather than one of those estates, a starting place among streets that show exactly what the reformers were reacting against: dense nineteenth-century blocks, back courtyards and busy avenues. From here the estates are spread out across the city, Britz to the south-east, Falkenberg to the far south-east, Siemensstadt and the Weisse Stadt to the north-west, so seeing them by bike is a satisfying urban tour.
Riding in Berlin is flat, busy and full of surprises. Cobblestones appear on older streets, tram tracks in the east, and cyclists everywhere, often on paths that cross your line at junctions. Traffic is heavy at rush hour, parking is a puzzle and the speed limits are generally enforced. On the plus side, the city's wide avenues and grid of streets make navigation straightforward, and the estates themselves are calm, leafy places where the bike can rest at the kerb while you walk.
Fuel, food and coffee are never far away. Kreuzberg itself is famous for its cafés, Turkish bakeries and döner stands, and for a mix of cultures that makes lunch an adventure. Close by you have the Landwehr Canal, the remains of the Anhalter Bahnhof and the Topography of Terror documentation centre, a sobering stop on the site of the former Gestapo headquarters.
Visit the estates in spring when the gardens bloom and the colours of Taut's façades glow against the green. Walk through the Hufeisensiedlung and imagine a family moving in from a cramped tenement in 1927, opening a window onto trees and sky for the first time. That is what the idealists of the Weimar years were building for.