Tour Carpe Diem is an important step forward in the evolution of La Défense toward pedestrian-friendly urbanism and environmentally responsible architecture. The 45,500 m² building is the first development to connect the raised esplanade—the "dalle" that continues the axis of the Champs-Elysées—and the urban fabric of the city of Courbevoie to the north. A pedestrian street leads to the building's lobby; at the level of the dalle, the main lobby is augmented by a seventeen-meter-high winter garden, a skylighted oasis at the heart of La Défense in which visitors can meet in an exotic vertical garden.
A monumental stair descends to a plaza on the Boulevard Circulaire, where a second front welcomes visitors at what was heretofore very much the back of the site. The building meets the Boulevard with a grand interior stair that ascends side-by-side with the exterior stair. The building's faceted facades reflect this dual orientation and catch the ever-changing Parisian light, giving the building a strong identity among the towers of La Défense. The building's thirty office floors offer 1,300 m² of column-free space configured to maximize light and views.
A rooftop clubhouse provides conference facilities including meeting rooms and an 80-seat dining room, all wrapped by an accessible roof garden that frames dramatic views over Paris. Tour Carpe Diem significantly exceeds French Haute Qualité Environnementale regulations for environmentally responsible development and achieved LEED-CS Platinum certification; it is the first building in France to receive these dual certifications. The building relies on geothermal wells at its main energy source. Additional sustainable design strategies include solar water heating, a heat recovery system, high-performance lighting, controls for daylight dimming, and occupancy sensors.