You're a major, progressive, car-hating European nation, with all the bike lanes you can muster. But while converting a roundabout to a standard four-way intersection, the roads suddenly get in the way of the bike lanes! What do you do?
If you're the Netherlands, you construct a highly-engineered, very beautiful and innovative RING that sits above the intersection, allowing bikers to enter and leave from any direction.
Unfortunately after they built it, they found that it was affected by tremendous vibrations, so they had to close it for six months and add dampers.
What they wound up with is very beautiful and functional. And a lot better than tunnels, which would have been cheap and invisible and not an attraction at all.
Source, with more pictures