The gradual transition to buildings lit up on the first day involves a multiplication of volumes. PB20-PB21 is a perfect example of this. The gigantic size of the various parts of the building, most of which are square in plan, is mitigated by their location straddling the esplanade and the natural ground. The materials used for the facades, stone and glass in different shades, complete the interplay of volumes. Access is via large porches that reveal the gardens of the interior patios.

The courtyard planted with acacia trees and third-generation buildings on a human scale gives the neighborhood a more intimate and friendly character. The limited number of architects on the site also ensures a certain homogeneity.

Michel Andrault (1926) and Pierre Parat (1928) joined forces in 1957 and occupied a prominent place on the French architectural scene for nearly forty years. Known for their work on housing (the Pyramides d'Epernay and Evry), they also designed major facilities such as the Palais Omnisports de Paris-Bercy.

In 1985, they entered La Défense and, like Henry La Fonta, established themselves as the most influential architects on the site. They accompanied its transformation for nearly ten years and designed several master plans. In terms of achievements, Michel Andrault and Pierre Parat participated in a dozen projects, including the restructuring of the CNIT and the Société Générale towers. In 1997, the Renaissance Hotel marked their last collaboration. Michel Andrault then continued his career by founding the Conceptua agency with Nicolas Ayoub.