Zoobrücke

Early proposals date to 1953; in 1962 the city council approved construction and held a design competition, won by Gerd Lohmer — who had already designed several Cologne bridges — together with a consortium of firms. Lohmer's original design called for a red paint scheme, but the bridge was finished in Cologne's characteristic bridge green. The crossing, initially dubbed the "North" Bridge, got its present name in 1963 via a reader competition in a Cologne daily newspaper: the zoo stands just 200 metres from the left-bank approach ramp. The bridge was inaugurated on 22 November 1966.

The Zoobrücke holds a world record: it is the longest-spanning box girder bridge supported by only a single main bearing, and the largest bridge of this structural type on the Rhine. Its sole pier stands asymmetrically close to the right bank; from there the deck extends to two slender supports on the left-bank promenade. The self-supporting roadway rests on two 4.5-metre-wide twin-cell hollow boxes whose profile reaches 10 metres in height above the pier and tapers to just 3 metres at the ends. The walls are stiffened against buckling by narrow sheet-metal webs — a technique borrowed from aircraft construction — which gives the bridge a noticeable, lively flex. Including both approach ramps, the total length comes to around 2.6 kilometres.

The Cologne Cable Car, opened for the Federal Garden Show as early as 1957, crosses the Zoobrücke. Its right-bank pylon initially stood in the way of the new bridge, so the cable car was temporarily dismantled. After public opposition, the pylon was shifted southward and the line extended into the Rheinpark. It has crossed the bridge diagonally ever since.

In 2000 the bridge's interior was opened to the public: for an installation by New York artist Serge Spitzer, 100,000 Kölsch beer glasses were placed inside the steel structure, and hard-hatted visitors walked a 600-metre route along a narrow catwalk starting inside the right-bank pier. In the 1970s, two objects recovered from the shipping channel and believed to be oil tanks were stored inside the pylons — when engineers drilled into them for inspection, they turned out to be live British bombs from the Second World War.