The Ampère e+ and City Défense buildings form a discreet ensemble within the district. Separated by a central alleyway, the two buildings are distinguished from one another by their shape: one is triangular in plan, while the other is angled. Their identical facades are a response to the need for buildings to evolve in shape, in order to improve working conditions and reduce energy consumption. Alternating white panels and reflective glass create a two-tone effect that changes with the color of the sky.

Agence Saubot was founded in 1964 by Roger Saubot (1931-1999) and François Jullien. The two architects specialized in high-rise commercial buildings, and worked with numerous international firms, most of them American. In 1985, they built the Bouygues Construction headquarters in Guyancourt, in partnership with Kevin Roche and John Dinkeloo.

In 1964, in association with the renowned Skidmore, Owings and Merrill practice, they took part in the Fiat Tower project (which became the Areva Tower in 1979). They went on to establish themselves as the architects of La Défense, and were involved in 11 projects, ensuring the transition to more energy-efficient and better-lit buildings (Total Coupole, France Télécom, Veritas offices...).
Roger Saubot and François Jullien went on to build the Disney Festival at Eurodisney in 1992, as well as the American Center - now the Cinémathèque française.