Pink Pipes

Since Berlin was founded in a very swampy area - the term ‘berl’ means swamp, Berlin therefore means swamp-city - the ground-water level is actually quite high. In the city centre it often lies very close to the surface which means that whenever a new building is constructed the foundations reach into the water and the construction site is constantly flooded by the ground-water.
Of course this water has to be pumped away constantly, which is done via the pink (and blue) pipes!
If you follow the pipes to one end you will always get to a construction site, if you follow them to other end you will always get to a canal or the river.
Berlin, Germany