A ceremony marking the first stone of ESO’s Extremely Large Telescope (ELT) has been attended today by the President of the Republic of Chile, Michelle Bachelet Jeria. The event was held at ESO’s Paranal Observatory in northern Chile, close to the site of the future giant telescope. This milestone marked the beginning of the construction of the dome and main telescope structure of the world’s biggest optical telescope, and ushered in a new era in astronomy. The occasion also marked the connection of the observatory to the Chilean national electrical grid.