Colossus

Arguably the world's first stored program computer, built at Bletchley Park, Buckinghamshire, in 1943. Designed to help decode enemy communications during World War II, Colossus was built by Thomas Flowers, a research engineer. The design of Colossus is attributed to Max Newman, a mathematician, but it also drew heavily on Alan Turing's concept of the universal machine. At the end of the war, Flowers was ordered to destroy all the blueprints for Colossus, and the computer was broken up and stored away. The existence of Colossus was kept an official secret for many years. Because of this secrecy, history has recorded that the first computer was ENIAC, built in the USA at the University of Pennsylvania in 1945. One of the ten Colossus Mk 2s built after D-day was since rebuilt in its original room at Bletchley Park.