Berlin's Waterproof Terminal

Berlin is a city where the water table is so high that anytime you do any kind of construction project in the city, you have to put big above ground pipes. The airport terminal was designed as you can see here so that trains would run right into the building. During this whole time, the ventilation system for those tunnels was trains moving through them. Deutsche Bahn had to spend 10,000 euros a day running empty trains back and forth so the tunnels did not develop fungus.