Palace of Industry and Trade (exhibition hall A)

The building of the Palace of Industry and Trade is an important component of the urban composition of the entire exhibition centre. Its ground plan, with the two V-shaped naves intersected by the curves of the side wings, determines the directions of the two main communication axes. The hall consists of a ferro-concrete structure with characteristic parabolic supporting vaults and glass walls, which enable the ideal lighting of expositions by daylight.
The original design by architect Kalous included a horizontal beam ceiling supported by semicircular arches. However, Josef Valenta, fearing excessive load on the supporting vaults, changed their profile to parabolic and replaced the ceiling with barrel vaults reinforced by lengthwise beams. The building of the exhibition hall lasted 230 days and required 50 trains loaded with building material. The exhibition naves intersecting in the representative area of the entrance rotunda were originally linked only by corridors with a roofed inner yard. In 1976 the inner yard was filled with administration facilities, designed by architects Ivan Ruller, Zdeněk Müller and Petr Uhlíř, whose glassed facade connects the main wings of the hall.
The 1980s saw a reconstruction of the entire building, during which the exhibition areas acquired built-in galleries and a heating plant so that the building could be operated year round. The overcrossings by Miroslav and Dagmar Velehradský also contributed to the year-round user comfort of the entire exhibition centre. One of the cylindrical connecting corridors on a rod structure with a spiral housing was also built to connect exhibition halls A and C. The exhibition hall is still in use, but the method of the installation of exhibitions in confined exhibition cells fails to profit from its generous spatial potential.