High Quality Content by WIKIPEDIA articles! The European Extremely Large Telescope (E-ELT) is a planned ground-based extremely large telescope for the optical/near-infrared range, to be built by the European Southern Observatory (ESO) on a mountain top in Cerro Armazones, Chile. The design comprises a reflecting telescope with a 39.3 metre diameter primary mirror, a 4.2 m diameter secondary mirror, and will be supported by adaptive optics and multiple instruments. On 11 June 2012, the ESO Council approved The E-ELT programme to begin construction of the telescope, pending agreement with the governments of some member states.