After less than 18 months of intense construction and landscaping work, the building has been completed, according to a statement from John Tenanes, vice president of global facilities and real estate.
The building touts green amenities, both of the leafy and sustainable varieties: It has a 3.6-acre rooftop garden that includes a 2,000-seat amphitheater space, and a reclaimed water system that's estimated to save about 17 million gallons of water a year, according to Tenanes.
The building, according to plans approved by the City Council in November 2016, totals about 523,000 square feet. It is connected to the company's Building 20, which was completed in April 2015.
The company is also working on its next office structure, Building 22, at 301-309 Constitution Drive. Revised plans for that roughly 450,000-square-foot office building and adjoining parking garage cleared the City Council last November.
Of the development process, architect Frank Gehry said, "All the things we learned doing Building 20 prepared us for Building 21. We were getting lessons in Facebook culture and were making a new kind of architecture within that culture."
Of the architectural designs, he said, "I feel like we're not turning our back on the neighborhood. We're talking to the architecture of the neighborhood so it feels like it belongs here."
As part of the project, Facebook has committed to building a two-acre park with a public plaza and event space to host events like its festival programs and mobile farmers' market. It is also planning to build a bike and pedestrian bridge over Bayfront Expressway that will provide easier access to the Bay Trail and Bedwell Bayfront Park.
The announcement of the building's completion follows months' worth of news that Facebook is continuing to expand its lease holdings throughout the Bay Area.
According to reporting by publications around the region, Facebook is snapping up new office space faster than a Hungry Hippo snaps up marbles.
In May, the company leased 1.18 million square feet in San Francisco and about 1 million square feet in Sunnyvale. In June, it leased about 750,000 square feet of office space in Fremont, an another 450,000 square feet in Mountain View.
In a written statement, Tenanes said, "To support our growth, we're expanding our Bay Area office locations in addition to our Menlo Park headquarters. Our regional growth plan is designed to locate workplaces closer to where people live and where there is supporting infrastructure like housing and transportation. We are invested in Menlo Park and it will be our headquarters for the foreseeable future."
Most recently, the company confirmed it is in discussions to lease additional office space in Burlingame.