Discover everything there is to know about the story of time, from the relationship between Greenwich and time to the people responsible for inventing groundbreaking, timekeeping instruments. Visit the Home of Time Discover how the Royal Observatory revolutionised the recording of world time, stand astride the Prime Meridian Line – the historic place where east meets west – and have a peek inside the Great Equatorial Telescope Visit the Royal Observatory Top things to discover What is Greenwich Mean Time? Everything you need to know about the historic international standard of civil time What is Greenwich Mean Time (GMT) - and why does it matter? What is the Prime Meridian and why is it in Greenwich? The Greenwich Time Ball and one time for all Who has the time? Our experts delve into the history of time – and reveal Greenwich's relationship with time The history of timekeeping Explore the evolution of time telling – and the treasures within our horological collections Our collections: A unique history of timekeeping Our collection of approximately 1000 horological objects covering marine, astronomical and domestic timekeeping Sundials For thousands of years, the sundial has told the time and divided the day. Which time is it? Next time someone asks you the time, you may enquire if they want to know the atomic, universal, civil, local, solar or sidereal time Which years are leap years and can you have leap seconds? Because the Earth takes a little over 365 days to orbit the Sun, we need to make adjustments to keep the seasons from drifting: leap years and even leap seconds Why do we change the clocks? Learn about the history of British Summer Time (BST) and Daylight Saving Time When do the clocks go forward in 2024? Marking the start of British Summer Time, the clocks 'spring forward' in March, meaning we'll lose an hour's sleep British Summer Time (BST) and Daylight Saving - understanding UK time changes Why does UK time change, and when was British Summer Time first introduced? Explore the history of BST and daylight saving The clocks that changed the world Discover how John Harrison's clocks helped to solve one of seafaring's greatest problems: finding longitude Learn more about the Harrison clocks What was the longitude problem? Clock themed books and gifts Shop Treasures of Royal Museums Greenwich £10.00 Beautifully illustrated and accompanied by extraordinary histories, this book is a celebration of 100 of the most important and exquisite objects in the Royal Museums Greenwich collections, including some of the most significant new acquisitions of the last ten years... Buy Now Shop Royal Observatory Greenwich John Harrison's H4-Inspired Gold Pocket Watch £175.00 A stunningly crafted, gold-plated half double hunter pocket watch inspired by John Harrison’s world-changing chronometer... Buy Now