The Giant Magellan Telescope (GMT) is one of the proposed next generation of extremely large optical telescopes. It will have a main mirror consisting of seven segments each of 8 metres diameter - so it will have seven times the collecting area and three times the spatial resolution of today's best telescopes. GMT will be used to study planets around other stars, the formation of stars from clouds of gas and dust, the assembly of the first galaxies in the early universe,and the intriguing mysteries surrounding black holes, dark matter and dark energy. Australia is aiming for a 10% share in the GMT, which is being built by an international consortium also involving major USinstitutions and Korea. It will be located on one of the world's best observing sites at Las Campanas Observatory, in the foothills of the Andes mountains in northern Chile. The GMT is currently in the design development stage and construction will take a further 10 years at an estimated cost of US$600M. Together with the Square Kilometre Array radio telescope, GMT will give Australian astronomers access to theworld's best research facilities.