With sudden, heavy rainstorms becoming more common, a new park design—capable of holding nearly six billion gallons of water—gives all that rain somewhere to go without flooding city streets.

As a coastal city, Copenhagen faces the risk of storm surges from rising sea levels. But it also faces an even larger risk of flooding from extreme rainstorms, which are becoming more common as climate change progresses. A massive new “climate park” is designed to capture water in sudden storms—nearly six billion gallons—to keep it from flooding streets and buildings when the sewer system is overwhelmed.

The park, called Enghaveparken, originally built in the 1920s in a lower-income neighborhood, was redesigned in a way that preserved its historic design while preparing for the realities of climate change.

“It was kind of a Catch-22 situation—how to preserve this park and redo it, and still make room for this insane amount of water,” says Flemming Rafn, a founding partner at Tredje Natur, the Copenhagen-based architecture firm that worked on the project for the City of Copenhagen along with Cowi and Platant.