These buildings may look like they’re overgrown with plants. But they’re designed to be that way! The apartment buildings in Milan, Italy, contain more than 20,000 trees and shrubs. 

All those plants, plus the soil and water they need to survive, weigh hundreds of thousands of pounds! Engineers built the towers out of a special type of concrete. It contains steel cables that are stretched tightly to withstand the extra weight. The plants are secured with wires so they don’t blow away.

Architects designed the towers to bring nature to people living in the city. “It is a house for trees and also for humans,” says architect Stefano Boeri.