A: London, England, United Kingdom
The idea of using three monochrome images to produce a color image had been experimented with almost as soon as black-and-white televisions were built. On July 3, 1928 Scottish inventor John Logie Baird demonstrated the world's first color transmission. He used scanning discs at the transmitting and receiving ends with three spirals of apertures, each spiral with filters of a different primary color; and three light sources at the receiving end, with a commutator to alternate their illumination.