When it was built in 1974, the CB21 tower caused quite a stir. Visible from the Place de la Concorde, it provoked a strong reaction from Parisians, even leading the President, Georges Pompidou, to speak out in Le Monde in favor of high-rise development in the area.

CB21 is characterized not only by its cruciform cross-section, but also by its structure combining a reinforced concrete core and metal floors, which in turn rest on metal columns on the façade.

Like most towers of its generation, it was the subject of a vast renovation plan designed to bring it up to high environmental quality standards. CB21 is the first building in the La Défense renewal plan.

Founded in 1941 by Wallace Harrisson (1895-1981) and Max Abramovitz, the Harrisson and Abramovitz agency is one of the most famous on the American East Coast. Active until 1976, it designed numerous office buildings, including the UN headquarters.

At the same time, both architects pursued independent careers. Harrisson, for example, designed the controversial Lincoln Center in New York. Familiar with French culture, the duo was one of the first on the other side of the Atlantic to be commissioned by Epad.