Stand on the Prime Meridian Line

Meridian building and gallery closures

Due to important restoration works, the Meridian Gallery and Building will be closed to our visitors as of 7th of January until 15th of February 2019. Flamsteed House, the Octagon Room, Meridian Line, Great Equatorial Telescope and Meridian shop will be accessible as normal. 

Essential information

Opening times: 
10.00–17.00 daily
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).

  • Grab an iconic selfie on the historic Prime Meridian Line of the world and share using #PrimeMeridian
  • Discover the remarkable story behind the reference line for Greenwich Mean Time (GMT).
  • Tickets to the Meridian Line and Historic Royal Observatory also includes admission to our Time galleries and Great Equatorial Telescope.
  • Look out for the green laser which marks the Meridian Line in the evening sky from the top of the hill in Greenwich Park towards the London Skyline.

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.

Download a copy of the latest Royal Observatory visitor leaflet to learn more about what to see and do (PDF, 1.3MB)

Find out more about the historic Prime Meridian of the World


We'd love to see your best photos. Share them using #PrimeMeridian.