California Academy of Sciences, San Francisco

The California Academy of Sciences in San Francisco boasts the world's most biodiverse living roof on any museum—a 1-acre expanse of native plants that insulates the building, absorbs 2 million gallons of rainwater annually, and supports local bird and insect populations. This green roof, combined with passive ventilation, natural light, and geothermal heating, reduces energy consumption by 30 to 35 percent compared to a conventional building of similar size.