ESO has signed a contract with the AdOptica consortium in Italy — ADS International and Microgate, partnered with INAF (Istituto Nazionale di Astrofisica) as subcontractors — for the final design and construction of the very challenging adaptive unit for the fourth mirror (M4) of the European Extremely Large Telescope (E-ELT). This mirror system will surpass any adaptive mirror ever made for a telescope and be the largest of its kind. The contract was signed by representatives of AdOptica and ESO at a ceremony at ESO Headquarters on 19 June 2015.