While we're talking about Devil's Bridges, Hamburg has one, too: It was built to make crossing the devil's ford easier, so called because there were so many accidents there people couldn't explain it otherwise. A carpenter was contracted, who is said to have made a pact with the devil, that the bridge may stay, at the price of the soul of the first living thing to cross the bridge. On inauguration day, then, the local reverend blessed the bridge and set off to cross it, when out of the bushes a rabbit appeared and sprinted across the bridge. A statute memorialises the occasion:

...the less exciting explanation is that back when Holstein was still under Danish rule there were two bridges close together, and the double bridge then turned into the devil's one. dövelt -> Düvel in Low Saxon makes a lot of sense but is boring.