Microsoft co-founder Bill Gates opened a new $15 million visitor center at the Bill and Melinda Gates Foundation's Seattle campus Feb. 4, and now that construction is finished, the software titan can focus on his foundation's goals. That means helping people all over the world gain access to medicine and immunizations, helping small farmers in Africa and, of course, improving access to technology. Since Bill Gates left Microsoft in 2008, his foundation has put together a $30 billion trust to accomplish these goals, and in January, Gates gave $750 million to the troubled AIDS fund.

At the end of 2011, there was some speculation that Gates would return to lead Microsoft, but he seems more determined than ever to lead his new life of philanthropy and activism. The new visitor center is a public space where people can see and learn about the foundation's work and its efforts to help people around the world live healthy and productive lives. It features exhibits about the work they support, a showcase of innovations and progress on some of the world's toughest challenges and information to help people take action. It's free to visit, open to the public and ADA accessible. Start the slideshow to see a tour of the new visitor center. Tell us in the comments if you think Gates will ever return to Microsoft.