You'd be surprised how little idea outsiders have of Silicon Valley's location. "Where is Silicon Valley?" I asked a few random East Coasters, and foreigners. North of San Francisco, answered two respondents, confidently. Another narrowed it down to somewhere between San Francisco and Los Angeles. "In California?" asked a third. A fourth wracked his brain: "Hmmm, San something". Even in an era of frictionless global information, so many articles about the Valley tech industry assume a modicum of geographical knowledge. Nobody ever writes: Google, based in Mountain View, a township some 30 miles south of San Francisco. Readers are too embarrassed to ask the dumb questions; and most reporters are too arrogant to answer them. Except us, of course. Here's the dummies' guide to Silicon Valley, with some of the major corporate landmarks. (It's south of San Francisco, by the way.)Click here for the interactive map.