The Computer History Museum is one of the great technology museums in the world, with a collection that spans from the abacus to the early internet. More than 100,000 artefacts, software titles, and oral history recordings document the full arc of computing history, from Babbage's mechanical calculators and room-sized mainframes to the first personal computers and the machines that mapped the human genome.
The permanent exhibition, "Revolution: The First 2000 Years of Computing," takes you through the story in rough chronological order, with actual working machines at key intervals. You can see the PDP-1 on which Spacewar! — one of the first video games — was played in 1962, and a Cray-1 supercomputer from 1976 that looks like a padded seat but once outpaced every other computer on Earth. If you grew up with personal computers, the Apple I and II display will stop you cold. There is also a strong archive on the history of software, including the source code for major operating systems and the papers of computing pioneers.
Allow at least three hours. The museum runs regular film screenings and public programmes. It's at 1401 N Shoreline Blvd, easily reached from downtown Mountain View on foot or by bike. Closed Tuesdays.