D is for Davidwache, the most famous police station in Hamburg and maybe in Germany. It has the smallest precinct of all police stations in Europe, only 0,92 km², encompassing less than half of St. Pauli. 14,000 people live there, but about 200,000 people come every weekend to party on the Reeperbahn and Große Freiheit.
It's right on the Reeperbahn which of course if the reason why it is so famous. Davidwache is actually the official name since 1970, usually police stations have numbers (the Davidwache is Hamburger Polizeikommissariat 15).
It was founded in 1840, when St Pauli wasn't even inside the Hamburg city walls. The station moved to the place it is located now in 1868 and the famous Davidwache was build in 1914, designed by Fritz Schuhmacher who has shaped the face of Hamburg considerably with his brick buildings. You can see a couple of old photos of the Davidwache here. The last photo shows the emblem of the Davidwache, designed by Richard Kuöhl, who also designed the decorations on the side of the building.
See what else D stands for with ABC Wednesday