In the old central part of Zagreb, among a block of buildings, a business facility is being built. The underground structure consists of 5 belowground floors, with maximum excavation depth of around 19 m. For construction of belowground floors the so-called “top - down” method is used. This method is useful to avoid long-term work on the construction of geotechnical anchors and tampering of nearby parcels. Excavation support is ensured by a 24.5 m long reinforced concrete diaphragm wall held by floor slabs of the underground levels. The reinforced concrete diaphragm wall is designed as a permanent structure and presents a vertical cap wall of the underground part of the building. Floor slabs are retained with steel columns, which are founded on drilled shafts ∅120 cm, 12 and 15 m of length.