The Gran Telescopio Canarias (GTC) will be, due to its features, the largest and most advanced telescope when it comes into service in 2003. Promoted by the Instituto de Astrofísica de Canarias (IAC), the GTC, with the decisive support of the State and the Autonomous Community of the Canary Islands, is the first "great science" project led by Spain and located in its territory. Its implementation will increase knowledge about the origin and evolution of the Universe and will allow the discovery of new and unknown celestial phenomena.