The Equatorial Group of Telescopes building with its unique design of six domes (labelled A to F) arranged around a central bastion, was constructed to house three reflecting and three refracting telescopes. Five were to come from Greenwich, the sixth being the addition of a new Schmidt telescope (planned for Dome C). Brian O'Rorke was the consultant architect for scheme which was completed in 1958.

This series includes a large set of drawings of the Equatorial Group of Telescopes building by Brian O'Rorke, including five colour drawings showing elevations, sections and plans (RGO 101/3/5/1/18-22). Also catalogued here are drawings and files relating to the friction drive units and dome shutter mechanisms; a set of drawings of the Yapp 36" Reflector, which was erected in Dome B; and a file on the Isaac Roberts 20" Reflector which was installed in Dome C by 1957 and used for photometric work until 1961.