The urban planning team Treuttel-Garcias-Treuttel et associés has designed a project for urban recomposition around twenty landscaped terraces, which run from the Arche to the Seine in Nanterre.

Like a spinal column, this vast public space recreates lateral connections between neighborhoods and restores links with La Défense and the Seine. The Terrasses are built as the residential and office buildings that border them are constructed.

• The Terrasses sequence at the foot of the Arche de La Défense. A 600-metre-long promenade bridges the gap between the Arche and boulevard Aimé Césaire.
• Les Terrasses de l'Arche begins on boulevard Aimé Césaire and ends in a belvedere, 6 metres above Place Nelson Mandela. This height makes it possible to take advantage of the view towards the Seine and the Arche, and to install business premises under the Terrasse. Alternating residential and office space, with ground-floor shops and facilities. An area has even been laid out on the Terrace opposite the residential units.
• The Terrasses de l'Université have been given a "country garden" theme. A play area and a planted promenade invite you to stroll around. It is connected not only to the Cœur de quartier project, but also to the Université Paris Ouest Nanterre-La Défense and the Cité des Provinces Françaises.

The A14 freeway runs beneath Les Terrasses. For safety reasons, it is therefore impossible to build on the Terrasses, but only on their edges. The 98 x 24-metre building blocks are subject to specific urban regulations, including compulsory alignment of the first floor, setbacks on the upper floors, and protection from the weather by means of canopies. The principle adopted by the Treuttel-Garcias-Treuttel team is based on an asymmetrical treatment of the axis, with building on the north side only, offering a long linear façade on the sunny side, and on the creation of 17 large urban terraces, following the morphology of the terrain (50 m difference in level between the base of the Arche and the Seine).

A Terrace is divided into five parallel strips corresponding to five different layouts:
 

• Boulevard de Pesaro, 22 m wide, lined with lime trees and lampposts, a two-way road with parking;
• A sidewalk with a bicycle path; the 7-meter-wide "noue", a densely planted garden, inaccessible to the public;
• 30-meter-wide planted terraces, with crosswalks for perpendicular traffic;
• The 20-meter pedestrian walkway, offering a double route along the terraces;
• Staircases along each new building, providing a horizontal surface for the development of ground-floor shops.

Water management is a fundamental element in the development of the project. Rainwater is collected and stored after filtering, for watering purposes, avoiding the discharge of fertilizers into the sewer. An overflow to the valley allows storm water to be held back for a few hours in order to control flows to the public sewage system.