Websites which you have also visited their physical headquarters:
Google (I stole a stick in Mountain View and gave a talk in NYC). ‎· Meg Vmeg
Audubon ‎· John B.
@meg At first I pictured a USB stick, then I thought no must be a tree branch, then some part of my brain said what this is google the USB thing could really be it. But now I'm back to the natural world mind picture. ‎· Micah
Yeah, natural sticks from stick trees. It took a while because I was limited to medians in the parking lot. For a talk at the Computer History Museum in...2011? Top 3 museums ever. ‎· Meg Vmeg
I'd really like to go to that museum, actually. ‎· Micah
@John in Manhattan? ‎· Micah
I haven't even visited where I work, never mind anywhere else. ‎· April
I worked for a web hosting company for a while so I was in the building with Martha Stewart's servers, among others, but I guess that's not what you mean. ‎· Christina Pikas
Soundcloud, textr, wire, teleport, kayak, wimdu, just to name the first I can remember. But surely a lot more of them ‎· fewdayslate
mailchimp ‎· ellbeecee
@micah: No, the one in DC (which I guess might be their policy office) ‎· John B.
WebMD's Ny Offices (granted, i was working there) ‎· hedgielib
Christina, I'm gonna count that. ‎· Micah
CNET, Ask Jeeves, Apple, Google ‎· Spidra Webster :pokerface: ‎· псы в рапиде
Google Russia, If we count the ones we work for - then plus,, ‎· будь счастлива и не выебывайся
@squadette: Hee hee! ‎· Spidra Webster
Nokia , u-blox, (long list of smaller companies I can't recall name) ‎· silpol
Not solely a website, nor started as one, but CNN ‎· ellbeecee