It is an astronomical observatory, with a rotating dome and hinged opening for the telescope to look out of. Inside it has a couple of steps up to the viewing platform.
Built from scratch to own design. The dome is supported on castors which enable it to rotate, and the central section of the dome has a two-fold hinged structure to provide a opening. The telescope is mounted on a tube concreted into the ground and isolated from the observatory structure to reduce vibrations. The telescope was a retirement present from work colleagues, and housing it in an observatory means I can go viewing without having to assemble it each time.