Largest single optical telescope

The Gran Telescopio Canarias (GTC) achieved 'first light' on 13 July 2007. Located on the island of La Palma, Canary Islands, Spain, the GTC has a main mirror made up of 36 hexagonal segments giving it a total diameter of 10.4 m (34 ft). The huge telescope and its 35-m (114-ft) dome cost 130 million euros to construct over seven years.