Earlier quoted context omitted.
I assume for Apple it is just the company store at their HQ they let people into? Or can you tour the rest of it?
You can walk around but the company store is pretty much it. Unique way to buy Apple t-shirts and stuff ;) IF you're into museums there's also the Computer History Museum next to Google in Mountain View. I haven't actually been there though.
"IF you're into museums there's also the Computer History Museum"
Even if you are not into museums it is my most recommended place to go in Silicon Valley. I have been here 3 years and never wanted to go walk around Google or Apple campus. But I guess it is something FREE to do.