It’s been two years since Bill Gates left his day-to-day role at Microsoft to concentrate on supervising the Bill & Melinda Gates Foundation–and his new enterprise is booming. Headquartered in a converted check-processing center in Seattle’s Eastlake neighborhood, the 10-year-old foundation plans to move into a 900,000-square-foot campus and visitors’ center near the city’s Space Needle next spring. The Gates Foundation opened a London office this year; it also has offices in Washington, Delhi, and Beijing, and 830 employees around the world, up from about 500 in 2008. With assets of $33.9 billion as of Dec. 31, 2009, and America’s two richest people–Gates and Warren Buffett–as trustees, the foundation plans to spend $3 billion in the next five to seven years on education. If there’s such a thing as a charity behemoth, the Gates Foundation is it.