In the heart of Seattle lies an urban oasis -- an acre and a half of pristine vegetation that most people will never see.

The parking garage at the Gates Foundation is Puget Sound's greenest roof. The plants are largely drought-resistant, thriving mostly on rainwater alone.

“The benefits that it brings to the community is that it provides oxygen for the air, it clears pollutants and it provides a habitat for insects and birds,” said Aaron Moses of the Gates Foundation.

Evening is your guide to Seattle and the Pacific Northwest. Watch it weeknights at 7:30 on KING 5 TV or streaming live on Connect with Evening via Facebook, Twitter, Instagram or email: