Around seven kilometers long, the main portion of Cologne's green belt winds along a half-circle from the Köln-Riehl bank of the Rhine to Luxembourg Straße. It's a sort of oasis for the city-dwellers, who use the parkspace for all kinds of recreation. For the traveler with bike, it presents a lovely opportunity to ride through parts of town beyond the inner city or make a complete circle (there are "Rundweg" markings) across the Rhine and back.
Grüngürtelstraße, Cologne, Germany