Early proposals for the campus, which was given the go-ahead by Menlo Park City Council last week, envisioned a bold, curving facade reminiscent of well-known Gehry buildings such as the Guggenheim Museum in Bilbao.
"They felt some of those things were too flashy and not in keeping with the kind of the culture of Facebook, so they asked us to make it more anonymous," said Craig Webb, a partner at Gehry's practice.
"Frank was quite willing to tone down some of the expression of architecture in the building," he told the Mercury News, explaining that they plan to disguise the white stucco building with a rooftop garden: "Our intent is that it almost becomes like a hillside, with the landscape really taking the forefront."
According to one Facebook employee, the 40,000-square-metre building will house 2,800 engineers in a single warehouse-like room.
"Just like we do now, everyone will sit out in the open with desks that can be quickly shuffled around as teams form and break apart around projects," said Facebook's environmental design manager Everett Katigbak in a blog post.
"The exterior takes into account the local architecture so that it fits in well with its surroundings. We’re planting a ton of trees on the grounds and more on the rooftop garden that spans the entire building," he added.
An underground tunnel will connect the Gehry-designed building with Facebook's existing campus over the road.
Gehry was brought in to design the campus last summer, with Facebook CEO Mark Zuckerberg stating at the time that he wanted an office with "the largest open floor plan in the world".
The social networking site's former Palo Alto headquarters was completed by San Francisco firm Studio O+A in 2009.
Facebook isn't the only Californian technology company expanding into larger headquarters currently, with construction now underway on Apple's ring-shaped campus in Cupertino designed by Foster + Partners, while Google recently revealed plans for a 100,000-square-metre campus in San Francisco Bay.
Images are by Gehry Partners LLP.