Ticketed

Essential Information

Location
Royal Observatory
Price Included with entry to the Observatory

Free entry for members . Not a member? Join now

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 using the Transit Circle telescope at the Royal Observatory. The cross-hairs in the eyepiece of the telescope precisely marked Longitude 0° for the world.

Visit the Royal Observatory

Image

What is the Prime Meridian?

A meridian is a north-south line, selected as the reference line for astronomical observations. By comparing thousands of observations taken from the same meridian, it's possible to build up an accurate map of the sky.

Any north-south line can be referred to as a meridian. The 'Prime' meridian however is the line defined as Longitude 0°: the spot from which all longitudes and time zones east and west can be measured.

Image

Why is the Prime Meridian in Greenwich?

There were two main reasons for the choice. The first was the fact that the USA had already chosen Greenwich as the basis for its own national time zone system.

The second was that in the late 19th century, 72% of the world's commerce depended on sea-charts which used Greenwich as the Prime Meridian.

By naming Greenwich as Longitude 0º, it would be advantageous to the largest number of people. Therefore the Prime Meridian at Greenwich became the centre of world time.

Learn more at the Royal Observatory

Visit the home of Greenwich Mean Time (GMT), the Prime Meridian of the world and London’s Planetarium.

Choose your tickets

A couple walks along the Prime Meridian Line in front of the historic Royal Observatory Greenwich building

Royal Observatory

  • Walk the Prime Meridian line
  • See the best view in London
  • Guaranteed entry time
  • Audio guide included
  • Planetarium shows not included
Adult from £18
Child from £9
BOOK NOW
A couple takes a selfie at the top of Greenwich Park, with the River Thames and Canary Wharf in the background

Royal Museums Greenwich Day Pass

  • Save 25% with combo ticket
  • Cutty Sark
  • Royal Observatory
  • Guaranteed entry time
  • Planetarium shows not included
Adult from £27
Child from £13.50
BOOK NOW

Member tickets

  • Unlimited free entry
  • Priority booking and exclusive events
  • Access using your membership card
Membership card number required
BOOK NOW
A father and son look through a porthole on the main deck of historic ship Cutty Sark

Become a Member

  • Unlimited entry all year
  • Royal Observatory
  • Cutty Sark
  • Planetarium Shows
  • Special exhibitions
Direct Debit One-off
Individual: £50 Individual: £60
Family: from £60 Family: from £70
JOIN TODAY