This is the first segment blank for mirror 1 (M1) of the ELT. Manufactured by SCHOTT, it was completed at the end of August 2018. M1 is the primary mirror of the ELT and, when completed, will be 39 metres in diameter and consist of 798 segments.

The ELT site on Cerro Armazones got its first foundations.

The first hexagonal segments for the main mirror of ELT were successfully cast by the German company SCHOTT.

At a ceremony in Garching bei München, Germany, ESO signed the contract with the ACe Consortium for the dome and telescope structure.

Agreement signed for the ELT's MAORY instrument, since renamed to MORFEO

ESO has signed an agreement for the design and construction of METIS

Agreement signed for the design and construction of HARMONI

ESO has signed an agreement to design and construct MICADO

At their meeting ESO’s main governing body, the Council, gave the green light for the construction of the ELT in two phases.

Part of the 3000-metre peak of Cerro Armazones was blasted away as a step towards levelling the summit in preparation for the construction of the ELT.

The civil works for the ELT began. The Chilean company, ICAFAL Ingeniería y Construcción S.A. (ICAFAL), started the construction of a road to the summit of Cerro Armazones.

The President of Chile Sebastián Piñera handed over the legal documents by which the Chilean government transferred the land around Cerro Armazones to ESO.

ESO’s governing body, the Council, met at the ESO Headquarters in Garching, Germany, and voted to start the Extremely Large Telescope (ELT) Programme.

The Republic of Chile and ESO signed an agreement regarding land for the ELT, including the donation of an area of 189 km2 around Cerro Armazones for the installation of the ELT as well as a concession for 50 years relating to the surrounding area, representing an additional 362 square kilometres, which will protect the ELT from light pollution and mining operations.

This night-time panorama shows Cerro Armazones in the Chilean desert. Cerro Armazones was chosen as the site for the ELT by ESO's Council. Cerro Armazones is a mountain at an altitude of 3060 metres in the central part of Chile’s Atacama Desert, some 130 kilometres south of the town of Antofagasta and about 23 kilometres from Cerro Paranal, home of ESO’s Very Large Telescope. Cerro Armazones was chosen from a final shortlist of including the peaks Ventarrones, Tolonchar and Vizcachas in Chile, and La Palma in Spain.

ESO Council decided to proceed with detailed studies for ELT. This study, with a budget of 57 million euro, made it possible to start the construction of the telescope. The preliminary design for the ELT shown here was published in 2006.