The oldest building consists of a main space approx. 50 metres long, with a short transverse wing at either end and a larger wing in the middle. The hospital extends over three floors and a basement. The façade is faced with so-called Ålesund stone with a veneer of råkopp granite quarried at Horn at the island of Løkta. The roof is hipped and decked with slate tiles (lappheller). The main space has a side corridor on the northern side, since patients' rooms traditionally used to face south, but there are mid-corridors in the wings. The operating theatres were original sited upstairs on the first floor of the middle wing, and here there are larger windows than in the other spaces. The entrance sections on the northern side are painstakingly finished with bevelled råkopp around the door openings and some of the original doors have been preserved. The copper ventilation towers contribute to the building's monumental aspect.