The foundation stone of the Radcliffe Observatory was laid on 27 June 1772. It was the third building in Oxford to be built from John Radcliffe's estate, after the Library and the Infirmary; and it was the second permanent Observatory in Britain, after the Royal Observatory in Greenwich. The positions of Sun, Moon, planets and stars observed and recorded there form a lasting contribution to astronomical knowledge.
The Observatory was built at the suggestion of Thomas Hornsby, the Savilian Professor of Astronomy, on a site close to the Radcliffe Infirmary, and in its essentials was finished by 1778. The Radcliffe Trustees also equipped the building with instruments made by the best instrument-maker of the day, John Bird.
Hornsby was appointed the first Radcliffe Observer, and using Bird's instruments, between 1774 and 1803 accurately made and meticulously recorded tens of thousands of astronomical observations. Successive observers continued this work and also compiled detailed meteorological data, and in due course photographic records were made.
In the 1930s the Radcliffe Trustees sold the Observatory site, and with the proceeds built a new observatory at Pretoria, South Africa, where the climate was ideal for astronomical observation.