Not paving over a river, but gardening over a roadway.

Thanks to A for the link.

German Autobahn to be Covered with Giant Public Park (Treehugger)

Germany's longest motorway is about to get one huge make-over; it will soon become a giant public park.

When it is all said and done, the A7 will sport a 10-foot-thick canopy starting with Hamburg's Schnelsen district, down to Stellingen and ending in Bahrenfeld. This is no simple task considering the cover will need to be over a 100-feet wide in some areas.