Images by Hamburg Marketing GmbH

Germany's A7 Autobahn is like a highway on steroids. The 500-mile, six-lane road runs the length of the country and handles 150,000 bat-out-of-hell drivers a day. That might improve life for traffic fetishists or people who regularly need to get from Denmark to Austria at 100 miles per hour, but people who live alongside the A7 have noticed that it's super noisy and kind of hard to cross. So they're putting a three-mile lid over the part of the A7 that runs through the city of Hamburg, and turning it into a public park.

The cars will still run underneath, in a tunnel with a 10-foot-thick ceiling. But on top there will be tree-lined promenades, plazas, and community gardens. This will take four years of work and the equivalent of a billion dollars, but the quality of life effects are likely to be staggering.

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