The T1 Tower was conceived of as a giant glass plate 200 meters in height, folded to the south along its vertical axis and cut by a gradual arc on its north face. This dynamic shape, whose appearance changes depending on the viewer’s vantage point, assures it’s insertion within the complex urban context and provides a new landmark for the La Défense skyline.Seen from the south, it resembles a vertical ship’s prow, cutting its way through the thicket of great towers at La Défense. From the east and west, it appears as an immense sail whose gradual curve and asymmetrical silhouette provide for a graceful transition into the adjoining neighborhood. Viewed from the north, it takes the form of a tall staircase climbing to the sky and disappearing as the façade curves out of view. The T1 tower also asserts it’s role as an urban tower, it’s shape deftly responding to the constraints of the complex site, contributing by it’s shape to the building of a new quarter. The tower marks the angle of a street and a boulevard to the south on which its façades are aligned. On the north it borders a new circular plaza centered on the main axis of its plane. At street level, the tower provides direct connections into the urban reality of Courbevoie, having it’s own postal address. The Tower’s horseshoe-shaped geometry provides for vast panoramic platforms at each level. It’s design associates high quality working conditions, functional efficiency, and high performance office configurations. The tower is oriented north-south with its giant curved glass plate tracking the sun’s path through the sky; a silk screened pattern on the towers curtain wall glazing enhances the towers thermal performance. The high level of insulation and reduced exposure of the façades reduces heat loss in the winter. Great attention was given to the buildings relationship with the environment. The architectural and technical systems provide for the comfort of all the tower population, and assure high health and safety performance. The tower is fitted with climate-controlled heating and lighting systems. All of these factors combined make the T1 Tower the first of a new generation of sustainable towers at La Défense, one whose architectural shape and environmental performance strongly set it apart from existing towers from earlier generations.