#Arecibo observatory

• Arecibo — A proper geographical name designating a coastal municipality in Puerto Rico, globally famous for its iconic Arecibo Observatory, a massive astronomical structure built inside a natural sinkhole depression. Structurally, the observatory served for decades as a cornerstone in astrophysics, ionospheric research, and SETI programs searching for extraterrestrial intelligence, and was also the origin of the famous 'Arecibo Message' beamed into space in 1974.