Gran Telescopio Canarias (GTC), the largest optical telescope in the world, with a mirror that has a diameter of 10.4 metres (34.1 feet). It is located at the Roque de los Muchachos Observatory on La Palma (2,326 metres [7,631 feet]) in the Canary Islands of Spain. The mirror consists of 36 hexagonal pieces, which can be moved separately from each other, and the shape of each piece can be changed. These two types of movements can compensate for the changes in the observed light that are caused by turbulence in Earth’s atmosphere. The telescope is mounted in a system that moves both in altitude and in azimuth to observe any point in the sky. Construction of the GTC began in 2000; it made its first observation in 2007. The GTC is operated by a consortium of four institutions: the Institute of Astrophysics of the Canary Islands, the National Autonomous University of Mexico, the National Institute of Astrophysics, Optics, and Electronics of Mexico, and the University of Florida.