SEATTLE (AP) — People are already joking it's a good thing the Bill & Melinda Gates Foundation isn't charging admission for its new visitor center, which showcases Bill Gates' multibillion-dollar philanthropy, not his computers.

But most people don't know what to expect from the glass-clad public space in front of the new headquarters of the world's largest charitable foundation.

Those who decide to peek in the windows or stop inside will find thought-provoking and even fun exhibits that encourage visitors to focus on how they can make the world a better place.

The center opens Saturday in Seattle, just steps from the Space Needle and Experience Music Project, two of the city's biggest tourist attractions. While it's not exactly a "museum of philanthropy," it's also not just a public promotion of the Gates Foundation's work.

"We know that there's interest and passion for our work. We haven't had a way to invite the public in to learn about our history, what we do and how we partner with others, and to think about what they can do," said Martha Choe, chief administrative officer of the foundation.

The Gates Foundation is one of a handful of large charitable foundations with buildings open to the public. Foundation staff visited a number of others for ideas, including the Franklin Institute in Philadelphia, the Mercy Corps Action Center to End World Hunger in New York City and the CDC Global Health Odyssey Museum in Atlanta.

But the creators of the Gates project also seemed to take inspiration from modern children's museums and science centers.

Bill and Melinda Gates put their own money into building the new headquarters campus, including the 10,000-square-foot visitor center.

The Gates Foundation's $33.5 billion endowment comes mostly from Bill and Melinda Gates, but also includes about $8 billion donated by billionaire Warren Buffett. A few years ago, the foundation also started accepting donations from the general public, but says it would prefer people make donations directly to the charities they support.

Gates focuses most of its dollars on fighting diseases like polio and malaria, helping poor farmers become more productive, and improving education in the United States. These topics and their complex solutions are explored at length in the visitor center.

The foundation moved in June to an architectural showcase in the center of its hometown. The entire project, including office and meeting space for nearly 1,000 people, cost about $500 million.

Inside the center, visitors are greeted by a room full of pictures, of the Gates family, foundation employees and people from around the world who have been touched by their generosity.

The first few galleries are focused on the foundation's projects, but visitors are also invited to sit down at a computer to say what they would do if they had their own billions to share. Those ideas scroll on the wall, right next to information about the real work the foundation is doing. In another spot, visitors can also take their own pictures for display larger than life on a wall, just like the pictures of foundation staff and beneficiaries.

Kids of all ages who get bored in museums where you can look and read but not touch will see right away that this is a place where hands-on play is encouraged.

In one of the first galleries, a wall of wooden blocks with dates on them can all be flipped to reveal photographs and bits of information. A large wooden globe is fun to spin, but it also works like a computer mouse to sail through a map of the world. Kids could also bypass the interactive displays and go straight to the fun room at the end of the walkway by the windows. There they'll find games and toys and other hands-on activities, including some doo-dads to put together. Who knows? They might just build a world-changing invention.