Closure of Great Equatorial Dome and Time for Navy Gallery

The Great Equatorial Dome and some galleries will be closed between 11:30am and 3.45pm on Tuesdays, Wednesdays and Thursdays until 24 August for daytime observation. Join the fun and see Venus in the daytime sky

Essential information

Opening times: 
10.00–17.00 daily
Admission: 
Included in venue ticket
Location: 
Royal Observatory, Meridian Line and Historic Royal Observatory, Meridian Courtyard
Free to members

Stand on the historic Prime Meridian of the World at Royal Observatory Greenwich, the home of Greenwich Mean Time (GMT).

It's a time honoured tradition for visitors to Greenwich to make the pilgrimage up the hill in Greenwich Park and get their photo taken on the official Prime Meridian Line  - will you join in the fun?

Since the late 19th century, the Prime Meridian at Greenwich has served as the reference line for GMT. The world's prime meridian divides 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.

To see the Meridian Line for yourself and grab that selfie, buy a ticket to the Meridian Line and Historic Royal Observatory. The entrance price also includes admission to our Time galleries and while you're here why not check out the amazing free Astronomy galleries.

Look out for the laser

During the evenings, the position of the Meridian Line is marked by a green laser in the sky, if you stick around until dusk you will see it stretching out from the top of the hill in Greenwich Park towards the London Skyline.

Find out more about the historic Prime Meridian of the World