Apple Park, in Cupertino, California, is the corporate headquarters of Apple Inc. Opened to employees in April 2017, the facility replaced the original Apple Campus, which opened in 1993. The building is one of the most environmentally friendly in the world, with power coming from the world’s largest rooftop solar installation as well as from the California Flats solar project. Air flows freely between the inside and outside of the building, providing natural ventilation and alleviating the need for HVAC systems during nine months of the year. The central campus also contains many drought-tolerant plants, and reusable water is used throughout the building.