The Meridian Line in Greenwich is the dividing point between the eastern and western hemispheres – Longitude 0°. You can stand on the Line at the Royal Observatory in Greenwich Park with one foot in each half of the earth.
The Meridian Line, or Prime Meridian, separates the eastern and western hemispheres just like the Equator separates the northern and southern. It’s been marked at Greenwich since 1884 in the courtyard of the Royal Observatory, where a stream of visitors take each other’s photograph standing on the line. It’s also marked by a green laser that stretches out across Greenwich every evening.