concrete structure, and a similar interpretation of public and private spaces, they also drew from the example of Medieval and Renaissance Italian town halls and public spaces, as well as from the bold granite structures of 19th-century Boston (including Alexander Parris' Quincy Market immediately to the east). Many of the elements in the design have been seen as abstractions of classical design elements, such as the coffers and the architrave above the concrete columns. Kallmann, McKinnell, and Knowles collaborated with two other Boston architectural firms and one engineering firm to form the "Architects and Engineers for the Boston City Hall" as the entity responsible for construction, which took place from 1963 to 1968. The architects designed City Hall as divided into three sections, aesthetically and also by use. The lowest portion of the building, the brick-faced base, which is partially built into a hillside, consists of four levels of the departments of city government, where the public has wide access. The brick largely transfers over to the exterior of this section, and it is joined by materials such as quarry tile inside. The use of these terra cotta products relates to the building's location on one of the original slopes of Boston, expressed in the open, brick-paved plaza, and also to historic Boston's brick architecture, seen in the adjoining Sears Crescent block and the Blackstone Block buildings across Congress Street. The intermediate portion of City Hall houses the public elected officials: the Mayor, the City Council members, and the Council Chamber. The large scale and the protrusion of these interior spaces on the outside, instead of being buried deep within the building, reveal the important public functions to the passers-by and are intended to create a visual and symbolic connection between the city and its government. The effect is of a small city of concrete-sheltered structures cantilevered above the plaza: large forms that house important civic activities. The cantilevers are supported by exterior columns, spaced alternately at and , which are steel-reinforced. The upper stories contain the city's office space, which are used by civil servants not visited frequently by the public, such as the administrative and planning departments. The bureaucratic nature is reflected in the standardized window patterns, separated by pre-cast concrete fins, with an open office plan typical of modern office buildings. (The subsequent enclosure of much of this space into separate offices contributed to the ventilation problems