The morphology of the building combines multiple modes of spatial organization: free-flowing spaces for the lower levels of heavy circulation, sequences of articulated chambers for the ceremonial level and open flexible space for the offices above. Vertical continuity is provided by the multi-level south entry hall, a forum for public events, by the northern concourse which with its terraced levels links the lower floors that are built into the hillside and a central courtyard, which can be reached from the city plaza and brings daylight into the interior of the building. The massive public access departments are accommodated at the lower levels which emerge as ramparts on New Congress Street. The public elements of government, the Council Chamber, the Councilors’ Offices and the Mayor’s Suite are placed at an elevated level. They are identified as expressive volumes of the interior spatial organization and as important features of the exterior. There is an underlying tripartite, classical order of a brick-clad base, a columnated middle level of concrete piers and the elements of government, and an attic of stepped tiers for the office floors above. The facades achieve their coherence by means of an elemental composition of aedicular motifs with emphatic hoods at the ceremonial level.

The fabric of the building is a combination of cast-in-place concrete, pre-cast concrete and masonry work. The complex weave of the visible pre-cast ceiling systems and the deep fins of the facades for air supply and shading incorporate elements of climate control into the tectonic expression of the building. The architectural matrix was developed for the anticipated modification and repartitioning of spaces as the City Departments’ functional requirements constantly shift over time. Electrical and mechanical systems generally have been accommodated within the modular structural elements of the ceiling plenum.

The use of an inventive technology and the allusion to historic precedent in the siting as well as the compositional scheme of the building result in a density of image, which is both modern and timeless in nature.