You are looking at the Gottfried Moller Rainwater Pump Station. Obviously, it pumps water! The interesting thing about it is the actual means used here.
In fact, the idea used here has been invented at least 2,300 years ago, presumably by the Greek mathematician Archimedes. At least, he left the first known description of it. Some scholars think that similar devices were in use in Babylon as early as 700 BCE! It is possible that similar machines cast in bronze watered the famous Hanging Gardens.
Image courtesy: Wikipedia
It's fascinating that an ancient idea is still used by our modern civilization to transport water from lower to higher elevations. It is found in pumps around the world, and one example you can see here.