The ubiquitous social network, Facebook, began at Harvard University, and for the first few years membership was open only to college students.
Facebook headquarters is now locate in Silicon Valley, on a campus formerly occupied by Sun Microsystems (before the company was acquired by Oracle Corporation).
There are few signs on the Facebook site. In the photo above, you can see the sign at the entrance, and just catch a glimpse of one of the buildings through the tree to the left of the sign.
1601 Willow Road
Menlo Park, CA 94025
Founded in February, 2004
9,200 employees (as of 2014)