National Museum of Computing, Bletchley

A true geek heaven is the National Museum of Computing in Bletchley which has a remarkable collection of computers ranging from the earliest electronic machines to fairly recent microcomputers. The highlight though is the ICL mainframe room full of "old iron".

Mainframes that filled rooms used to run the world, though have less power than the average smart phone these days. Of course thats not the whole story, mainframes were designed to munch through tens of thousands of records and transactions. You wouldn't really want to use an iPhone to calculate and print payroll for a few hundred thousand employees overnight!