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The museums, the machines and the men and women who worked it out: laboratories kept as they were, beam engines under steam, the tunnel, the barrier, the roofs, and the plaques on the houses where the ideas came.
The hill where the world's clocks were set, and where the longitude problem was finally solved.
MuseumsEngineering landmarksGo inside
Also in Museums.
Charles II founded the observatory in 1675 for one practical reason. A ship could work out how far north it was from the height of the sun, but not how far east or west, and ships were being lost for want of it. The astronomers here were set to map the stars accurately enough that a navigator could read the sky as a clock. Wren designed the house on the hill, and it is named for John Flamsteed, the first Astronomer Royal, who spent forty years measuring the heavens from it.
The other answer came from a carpenter. John Harrison spent his life building clocks that would keep time at sea through damp, heat and the roll of a ship — if you know the time at Greenwich and the time where you are, the difference is your longitude — and his sea clocks are here, three of them still ticking. Outside, a red ball has dropped down its mast at exactly one o'clock every day since 1833, so that ships in the river could set their chronometers by it before sailing.
Greenwich became the world's zero first by habit and then by vote: British charts were drawn from this meridian, most of the world's shipping used British charts, and a conference in Washington made it official in 1884. That is why the line in the courtyard is where east meets west, and why the world's time zones are counted from a hill in south-east London. The astronomers left for darker skies in the 1950s; the buildings, the instruments, the clocks and the view stayed.
Step-free access
| Monday | 10:00 – 18:00 |
|---|---|
| Tuesday | 10:00 – 18:00 |
| Wednesday | 10:00 – 18:00 |
| Thursday | 10:00 – 18:00 |
| Friday | 10:00 – 18:00 |
| Saturday | 10:00 – 18:00 |
| Sunday | 10:00 – 18:00 |
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Data is compiled from public sources including OpenStreetMap, under the ODbL. Hours change often, so check before making a journey.