Small correction, Colossus was designed to break the Lorenz cypher (which was considerably more complex than Enigma). The machine itself was designed by Tommy Flowers (not Turing), who was a post office worker who had previously worked with vacuum tubes and thought it would be possible to build a programmable computer with them. After the war Flowers applied for funding to build a similar machine (Colossus being top secret) and was denied on account of the idea being impractical.

The machine Turing is famous for his work on was Bombe, which was designed to crack Enigma.