The home of GMT
We're making improvements. As a result the Meridian Gallery will close from 7 January to 15 February. The rest of the Royal Observatory, including the Meridian line, will be open as normal. Visit the home of time
Stand on the historic Prime Meridian of the World at Royal Observatory Greenwich, the home of Greenwich Mean Time (GMT).
Since the late 19th century, the Prime Meridian at Greenwich has divided the eastern and western hemispheres of the earth - just as the equator divides the northern and southern hemispheres.
In 1884 the Prime Meridian was defined by Transit Circle telescope at the Royal Observatory which was built by Sir George Biddell Airy, the 7th Astronomer Royal, in 1850. The cross-hairs in the eyepiece of the telescope precisely defined Longitude 0° for the world.
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