The Effelsberg 100-metre Radio Telescope is a radio telescope in the Ahr Hills in Bad Münstereifel, Germany. Inaugurated in 1972, for 29 years the Effelsberg Radio Telescope was the largest fully steerable radio telescope on Earth, surpassing the Lovell Telescope in the UK. In 2000, it was surpassed by the Green Bank Observatory's Robert C. Byrd Green Bank Telescope in Green Bank, US, which has a slightly larger elliptical 100-by-110-metre aperture.