Royal Observatory Greenwich

A Really Good Day OutEmma H, Trip Advisor


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Royal Observatory, Blackheath Avenue, London, SE10 8XJ

Opening Times

Mon-Sun: 10am-5pm 
Closed 24-26 December
Last admission: 4.30pm
From Thursday 21 July until Saturday 3 September, the Royal Observatory will extend its opening hours until 18.00.
The Royal Observatory Greenwich operates seasonal opening hours so please check before visiting.

Royal Observatory Greenwich

The Meridian Line

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 an audio guide which brings the story to life. While you're there, why not check out the modern Astronomy Centre where you can unravel the mysteries of the cosmos at the free interactive galleries, see stunning images of space from all around the world at the annual Insight Astronomy Photography of the Year competition and get your hands on a 4.5-billion year-old meteorite.

Decades before the first ball dropped in New York's Times Square signalling the dawn of a new year, London had its own version that told accurate time every day to Victorian Londoners. The bright red Time Ball on top of Flamsteed House is one of the world's earliest public time signals, distributing time to ships on the Thames and many Londoners. It was first used in 1833 and still operates today.

Each day, at 12.55, the time ball rises half way up its mast. At 12.58 it rises all the way to the top. At 13.00 exactly, the ball falls, and so provides a signal to anyone who happens to be looking. Of course, if you are looking the wrong way, you have to wait until the next day before it happens again.

The Time Ball drops at 13.00 GMT during the winter months and 13.00 BST during the summer.

What did people do before there was a time ball?

Only the richest people could afford to buy clocks and watches of their own. Most people relied on public sundials to tell the time. This led to different local times across the country, with clocks on the eastern side of the country about 30 minutes ahead of those in the west.

The difficulties created by everyone using their own local time eventually led to the creation of Standard Time based on the Prime Meridian at Greenwich.


Ticket types

General Admission


Adult (16+)


Child (5-15)


Concession (Student with valid ID and seniors 60+)


Family (2 adults, 2 children)


Children under 5 years old


There is no fast track counter at Royal Observatory Greenwich, simply present your voucher at the ticket counter. 

The Royal Observatory’s terms and conditions apply to all Where Pass visitors. For more information, click here.

Best time to visit*


* Based on least busy times

Recommended visit length

2 hours


  • Cutty Sark (for Maritime Greenwich)
  • Greenwich
  • Island Gardens


  • Maze Hill
  • Greenwich

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