Prime Meridian Line

About

The Prime Meridian Line at the Royal Observatory Greenwich marks 0° longitude, the reference point from which all world time zones are measured. Visitors can stand with one foot in the eastern hemisphere and one in the western — a classic and endlessly photogenic moment — while the Royal Observatory museum tells the fascinating story of longitude, time-keeping, and astronomical science. Entry to the observatory costs; the meridian line in the courtyard is visible from outside for free.