The Meridian line was established by Sir George Biddell Airy, the seventh Astronomer Royal.
The line was chosen as the global reference point at the 1884 International Meridian Conference.
The brass strip is now positioned according to the IERS Reference Meridian, which sits slightly offset from the historical Airy Transit Circle line due to modern satellite measurement.
The Shepherd Gate Clock is a slave clock, driven electronically by a master clock inside the observatory.
The Prime Meridian is the reference point for the Coordinated Universal Time (UTC) standard.
The Royal Observatory was commissioned by King Charles II in 1675 to solve the problem of determining longitude at sea.
The red time ball atop the Flamsteed House drops daily to provide a visual time signal to ships on the River Thames.
The site uses a specialized 24-hour clock face to distinguish between day and night cycles.
The Prime Meridian at the Royal Observatory in Greenwich serves as the official reference point for world time, marked by a brass strip set into the courtyard cobblestones. This longitude line, defined as 0° 0' 0'', divides the Eastern and Western Hemispheres. The site hosts the historic Airy Transit Circle, the telescope used to define the Meridian line in 1851. Visitors can physically stand with one foot in each hemisphere. The complex includes the Shepherd Gate Clock, which has provided Greenwich Mean Time to the public since 1852. The museum grounds house the Octagon Room, designed by Sir Christopher Wren as the primary observation space. Astronomical instruments and navigational tools are displayed throughout the galleries. The site is managed by Royal Museums Greenwich. It remains a functional historic site tracking celestial movements alongside its role as a tourist landmark.
The brass strip in the meridian courtyard where you can stand with one foot in each hemisphere.
Book your timed entry slot well in advance as the site frequently reaches capacity.
Download the site's digital map before arrival to locate specific historical instruments efficiently.
Prioritize visiting the interior galleries before standing on the line to understand the historical context of the measurement.
Do not mistake the modern GPS-aligned meridian line markers found elsewhere in the park for the historical brass line at the observatory.
