Observatory

The Observatory, built in 1839-40 by Anthony Salvin for the University, stands slightly away from Potters Bank in Durham. It is constructed of coursed squared sandstone with an ashlar plinth, quoins and dressings. The roof is hidden, but has a copper-clad dome. The building has a Greek cross plan with single-story extensions across the north and south sides.

The central range is two stories high with three bays, while the front and rear ranges are single-story and also have three bays. In the projecting central bay is a six-panelled door and overlight, flanked by long, narrow sash windows. Additional sash windows are located under the eaves. The upper floor features four pediments and a central bay that projects under a wooden pediment, containing a sash window. Glazed doors on either side open onto the roof of the ground-floor extension. All sash windows have glazing bars, flat stone lintels and projecting stone sills. A prominent gutter cornice runs continuously with the pediments.

Inside, the upper floor is lined with beaded tongue-and-groove boarding. A staircase features turned newels, square rods and a round handrail with a ramped section. The dome is boarded and supported by a rack-and-pinion gear system.