True, the Bill and Melinda Gates Foundation got the land for its new building at a fire-sale rate from Seattle taxpayers, paying $22 million in 2005 for a $72 million property under a sweetheart deal arranged by then-Mayor Greg Nickels. But the end product is a $500 million gem: two dueling boomerang six-story glass buildings flooded with air and light, and paneled with white-board walls so that the Foundation's 1,500 or so employees can jot down random thoughts as they occur. With a total of 900,000 square feet of office space on 12 acres east of Seattle Center, the building is designed to outlive us all, the Foundation included, since it is to dissolve 50 years after Bill and Melinda's deaths. Features unveiled at the recent opening include an under-floor air distribution system for ventilation, a one-million-gallon rainwater storage system used for irrigation and toilets, and several "living roofs," which provide habitat for birds and bugs. Though private, the new campus includes an 11,000-foot visitors center open to the public and the adjoining Seattle Center garage. RICK ANDERSON 500 Fifth Ave. N., 709-3100, gatesfoundation.org