Facebook CEO Mark Zuckerberg and his wife are donating $5 million to help expand a community health center in Silicon Valley.

The gift—announced Wednesday—will cover part of the $29 million cost for adding another facility to the Ravenswood Family Health Center in East Palo Alto, Calif. That's not far from Facebook Inc.'s headquarters in Menlo Park, Calif.

The new building is expected to be complete next year.

The 29-year-old Zuckerberg has become one of the world's richest people since he started Facebook's at Harvard University nearly a decade ago. Forbes magazine estimates his wealth at $19 billion.

Zuckerberg has been funneling some of fortune into philanthropy. Last year, he and his wife, Priscilla Chan, donated Facebook stock valued at $900 million to the Silicon Valley Community Foundation.

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