London, England: Royal Observatory in Greenwich, tourists gathered around Prime Meridian Line (Greenwich Meridian, International Meridian)

England, London: Royal Observatory in Greenwich, legs of people crossing Greenwich Meridian line

London, England: Royal Observatory in Greenwich, greenwich Mean Time (GMT) displayed on digital clock at entrance

London, England: Royal Observatory in Greenwich, weather vane and time ball on Observatory roof

London, England: Shepherd Gate Clock at entrance to Royal Greenwich Observatory

London, England: Panning shot of the Royal Observatory in Greenwich

London, England: Royal Observatory in Greenwich, Shepherd Gate Clock