photo: Miran Kambič

The exhibition and retail pavilion inside the Postojna cave is the first underground post office building in the world. The aim of the project was the renovation of a pavilion in the Concert Hall deemed inappropriate functionally and material-wise. The design would as well replace previously inappropriate visitor sanitary facilities located at the platform with new ones within the structure and connect them to a new biological treatment plant. The entire construction was possible only within the maximum dimensions of the partly demolished existing structure, while the specifics of construction in an underground cave required the use of inorganic construction materials appropriate for such conditions, adjusted to simple transport by the cave train and appropriate for manual fitting.The entire construction and fitting of construction elements observed nature protection requirements for the smallest impact on the value of nature possible. The concept of sustainability is also reflected in the heating system and ventilation and, last but not least, the first underground biological treatment plant in Slovenia.The exhibition and retail pavilion is designed in two parts. The pavilion part is a transparent, passable area with four entrances/exits, designed within a longitudinal volume in the form of the letter S, thus reflecting the wall of the underground hall. The volume is structured in a manner that directs the flow of visitors and points to entrances and exits.In the renovated service part of the structure, service areas and new sanitary facilities for the visitors of the postojna cave were provided as well as connected to the treatment plant on the level of the platform. The interior of the structure functions as a uniform, flexible space with installed floor plugs for plug-in exhibits and movable equipment. The volume of the exhibition and retail area is transparent throughout the entire interior height, functioning as an extension of the concert hall.The exhibition and retail area is flexible, as it is equipped with floor plugs prepared for plug-in equipment elements or exhibits. Other equipment elements in the exhibition niche can also be plugged in as desired to wall holders according to required exhibition or retail purposes.