“Berlin is surrounded by several lakes, and is home to the river Spree. Not to get into too much detail, it simply means that the ground Berlin is built on is quite marshy. […] With groundwater in Berlin existing just two meters under the city’s surface, consequently, it is impossible to dig any tunnels without the risk of flooding the German capital. […] Thus, the pipes surrounding Berlin serve to pump water from the ground and transport it to the canals, allowing both together to drain the basements of the city and to facilitate the urban works. For more than a century already, a company named ‘Pollems’ has been responsible for the system.”