Full-size Mock-up of World's Largest Telescope Mirror Built at ESO's Open House Day

On Saturday 15 October 2011 ESO opened the doors of its headquarters in Garching bei München, Germany, to the public. Throughout the day, thousands of visitors had the chance to help build a full-size mock-up mirror of the European Extremely Large Telescope (E-ELT) -- the largest planned telescope in the world -- and to experience many other aspects of ESO's work.