Arecibo Observatory (NAIC, National Astronomy and Ionosphere Center) is a 305m Radio Telescope in Puerto Rico built using a depression in the ground. It is the largest single-Aperture telescope. It uses its full 305m when aimed vertically, and can be aimed to roughly 20deg from the zenith, though its effective aperture is reduced.
European VLBI Network (EVN)
GALEX Arecibo SDSS Survey (GASS)