Astrophysics is fundamentally an observation driven science, where each new technological step allowing us to see further, fainter and in finer detail has answered numerous questions, and posed innumerably more. Building bigger and bigger telescopes has therefore been central to our understanding of the Universe for over 400 years. In this talk, Dr Clarke will review the history of large telescopes through ages, including the key technologies behind them from silvered glass to adaptive optics. He will explain how this has led us to the cusp of a new era of "Extremely Large" telescopes, and in particular look at the largest of these; the 39 meter European Extremely Large Telescope (E-ELT), in which the UK is playing a central role. With its combination of huge light collecting area and advanced instrumentation, it will take images 15x sharper than the Hubble space telescope, characterise the atmospheres of planets around other stars, and be sensitive enough to study galaxies at the very edge of the visible Universe. Who knows what new questions it will raise!