ESO was created in 1962 by European astronomers who, then only having access to northern skies, wanted to see what the southern hemisphere had to offer—half of the astronomy to be done! Member European states originally included Belgium, Germany, France, Netherlands and Sweden, and now include Denmark, Switzerland, Italy, Portugal, United Kingdom, Finland, Spain, Czech Republic, and Austria. Whew! The headquarters are located near Munich, Germany, and employs somewhere around 700 staff at a budget of 135 million euro annually. This all requires a lot of cooperation from a number of scientists and politicians of very different backgrounds, and ESO manages this with a wrinkle, making them the model of scientific and political cooperation.
Since then, discoveries have included evidence for the black hole at the center of our galaxy, Sagittarius A*, the furthest (and thus oldest) gamma burst, the first picture of an exoplanet, and the most distant galaxy yet seen. It's also proven to be the single most successful hunter of exoplanets. Pretty cool, huh?