Darla Nickel, Head of Berlin's Rainwater Agency poses next to a rainwater retention basin, part of the "sponge city" concept adopted for the 52 degree Nord residential complex, in Berlin's Grunau district on May 17, 2024. In two years' time, a massive hole in the heart of Berlin will become the German capital's biggest reservoir, capturing an increasingly precious resource -- water.
Once a swamp centuries ago, Berlin has gone from a city trying to keep its abundant groundwater from overflowing to one scrambling to keep its forests green. (Photo by John MACDOUGALL / AFP)