Based on the design of architect Nikola Dobrovic, the Student Union Hostel was built in Dubrovnik settlement of Montovjerna (Croatia) between 1938-1940. The concise geometrical form of the building was determined by its constant width of 6m, that corresponded to the minimal dimensions of the rooms and lateral corridors inside the building. The outer walls were cladded in rough stone with continual joints, thus forming the modular matrix fixed at 25cm with discontinuity in the vertical direction. In an adaptation from 1954, a new lateral annex was added, the interior arrangement of the rooms was modified and the disposition, size and type of the windows were significantly changed.