An optical and infrared telescope being built by the European Southern Observatory. It will be sited on Cerro Armazones at an altitude of 3046 m in the central Atacama Desert, Chile, some 130 km south of the town of Antofagasta and about 20 km from Cerro Paranal, home of ESO’s Very Large Telescope. Its main mirror will have an aperture of 39 m and consist of 798 hexagonal segments, each 1.4 m across. A sophisticated adaptive optics system will be used to sharpen the images. The ELT is scheduled for completion in 2024.

http://www.eso.org/public/teles-instr/elt/ Official telescope website.