Computers: ENIAC,   Philadelphia, PA   1945.

Machines for doing complex mathematical calculations have roots dating back many thousands of years to the Chinese abacus, a set of counting beads in rows on a frame. But by 1945, ENIAC - the Electronic Numerical Integrator and Calculator - had been born. It took up a very large room and had its own air conditioner. Now, thanks to developments such as the computer chip, a computer with the same capability can fit into the palm of your hand.