In 2001 the Tokyo city government said that all new buildings must have a garden on their roof. Plant don't absorb so much heat from the sun. The government hopes roof gardens will make the city a cooler place. Plants also help to fight air ollution.
"The garden's also a nice place to sit,says Yoko Mori, who works in the Atago Building. I often come up here to eat my lunch. Japan's beautifulc gardens have always been famous. And now roof gardens are helping tomake the enviroment better.