The Royal Observatory Greenwich is located in Greenwich, London, and was established in 1675. It played a crucial role in the history of astronomy and navigation, particularly in the development of longitude measurement. The observatory is famous for the Prime Meridian, which marks 0 degrees longitude. Today, the Royal Observatory is part of the National Maritime Museum and serves as a museum and educational center. Visitors can explore its historic buildings, view astronomical instruments, and learn about the significance of timekeeping and navigation in maritime history.