Generally regarded as the birthplace of Silicon Valley, Hewlett-Packard's (in)famous garage. It's still there:
367 Addison Ave.
Palo Alto, CA
N 37* 26' 34.9" W -122* 9' 17.5"
you might want to check out this photo with a dedication plate: http://www.videoi.com/~pietro/NerdTour/images/HPGarage.jpeg