Magnetic Pavilion unearthed in Greenwich Park

Local volunteers and over 200 schoolchildren assisted in excavating an area once home to scientific instruments designed to track variations in the Earth’s magnetic field.

Archaeological work near the Royal Observatory in London’s Greenwich Park has uncovered the remains of a pavilion built in the 19th century to help scientists take magnetic readings, and traces of a 1930s telescope building.

Image: The Royal Parks.

The Royal Parks’ community archaeologist Andrew Mayfield led local volunteers and over 200 schoolchildren in excavating a site known as the Christie Enclosure – an area once home to scientific instruments designed to track variations in the Earth’s magnetic field – this summer.

The instruments themselves were housed in the Magnetic Pavilion, a specially constructed wooden structure with a concrete base that was built in the 1890s. ‘All of the metalwork in it would have been non-magnetic,’ Andrew told CA, explaining that the magnetically neutral environment was a necessary precondition for taking accurate magnetic readings. The development of the railways threatened the precision of the observations, however, so the work was relocated to Surrey in the 1920s. New structures were then erected in the enclosure, including a domed building completed in 1932 to house the Yapp Telescope – the largest telescope the observatory had ever owned — after which the pavilion was demolished. These buildings were torn down in the late 1950s, however, when the organisation moved to Herstmonceux in Sussex (where the Yapp Telescope can still be seen to this day).

The enclosure was then returned to parkland, and since then it has lain unmarked and largely unknown to passers-by. During their investigations, though, Andrew and his team found around a third of the pavilion’s foundations (PICTURED ABOVE), alongside copper nails, copper sheeting, and pieces of lead roof. The team also located part of the concrete base of the telescope building (complete with drains and electrical conduits), which has otherwise been ‘heavily robbed away’, Andrew said. ‘We don’t have the architectural plans for the Yapp building, so we’re actually finding lots of the detail that we wouldn’t have if we didn’t run the excavation,’ he added.

The work was carried out as part of ‘Greenwich Park Revealed’, a four-year project supported by The National Lottery Heritage Fund and The National Lottery Community Fund. A new interpretation of the site will be installed in the area in due course. For more about the site, see, and for more about the observatory’s past, see – a website created by Graham Dolan, a leading expert on the history of the Royal Observatory.