Built in 1963, Puerto Rico’s Arecibo Telescope was built in 1963. It is the second-largest single-dish radio telescope in the world. It was in news recently because of its collapse. It is owned by the US National Science Foundation. It is known for its finding that Mercury rotates in 59 days and not 88 days as previously thought. Apart from its scientific contributions, it is also a cultural symbol for Puerto Rico. It attracted around 90,000 visitors annually.