1600 Amphitheatre Pkwy - Headquarters (now Googleplex)
Sold to Google in 2003.
1401 N Shoreline Blvd - SGI Building 20 (now Computer History Museum)
The mayor of Mountain View, CA used an Onyx RealityEngine2 to "walk through" this model of a proposed new Silicon Graphics Office Building in a ground-breaking ceremony. The new building, which is Silicon Graphics' training and support center, is now located at the corner of Shoreline Blvd. and Pear Ave. in Mountain View. It opened in 1995.
900 North McCarthy Blvd - Current (as of 2015)
This appears to be the corporate headquarters after the Rackable acquisition, though this information may now be outdated since the HPE buyout.