This parking garage in Cologne is, on the authority of my driver, Europe’s largest. It stretches over 4KM, but only has three entrances. Many of the parking stalls have elevators that allow one car to be parked above another. According to my driver, it has been built to withstand the periodic flooding of the Rhine, although any cars left in the lot will be completely submerged.
Wow! Can’t even see the other end!