From an eyesore to a defining feature

The Tours du Pont de Sèvres office towers on the south-western outskirts of Paris, which were built in 1975 and had since deteriorated into an eyesore, were long a potent symbol for the rise and fall of the French automotive industry. Dominique Perrault won an international architectural competition in 2007 with his facelift of the tradition-steeped towers. A central element of his concept for refurbishing, restructuring and expanding the colossal structures was the agora spanning some 5 000 square meters. Gaëlle Lauriot-Prévost from Perrault’s firm designed the foyer of this area as a meeting point and junction for residents and employees from a total of ten towers. To structure the 1 500-square meter hall, she chose ceiling-high room dividers made of Escale stainless steel mesh from GKD – GEBR. KUFFERATH AG. Targeted lighting of the metallic structure creates a variety of reflections, which underline the bright, inviting character of the representative lobby.

Boulogne-Billancourt is located beyond the Boulevard Périphérique, the highway that encircles Paris. This commune with almost 120 000 residents shares a border with the 16th arrondissement of the capital city and has therefore long been viewed as the unofficial 21st arrondissement of Paris. The community borders the Seine on three sides, while the legendary city park Bois de Boulogne begins in the north. Below the former main Renault factory on an island on the Seine, the Pont de Sèvres connects Boulogne-Billancourt with the Parisian suburb of Sèvres. Alongside the metro station there, the tower complex designed by architects Daniel Badani and Pierre Roux-Dorlut in 1975 was also named after this important connecting bridge. The complex comprised three tall office towers of different heights with a hexagonal footprint, which were each in turn connected to three shamrock-shaped ensembles. The largest, the Tour Vendôme, had a usable area of 31 700 square meters over 23 floors, the second, the Tour Chenonceau, offered 28 500 square meters over 15 floors and the smallest, the Tour Amboise, spanned 16 000 square meters on nine floors.

The new millennium heralded a comprehensive transformation process for the somewhat shabby Trapèze quarter and the Île Seguin. Within the scope of this change, the entrance to Boulogne-Billancourt was to be given a facelift, along with the Tours du Pont de Sèvres. One year after winning the competition for their redesign, Dominique Perrault started to plan the design for the building complex, renamed CityLights, in 2008. In the first phase, he added a fourth hexagon to the former Tour Chenonceau, today known as City 2, in doing so expanding the office area from 76 200 to 86 600 square meters. After four years of complementary studies and the comprehensive removal of asbestos from the old towers, the refurbishment work began in 2013. All façades and floors were completely replaced; only the forming and bearing concrete structure of the tower blocks was retained.

Illuminating landmark
For the new façades, Perrault designed a combination of polished aluminum frames and panels with glass. Six to ten-stories-high prism-style folded frame constructions were added, which were coordinated with the differing heights of the towers. This optical interruption of the linear window pattern in both vertical and horizontal directions dilutes the monumental nature of the towers. Perrault integrated special LEDs that sparkle like a diamond bracelet during the night in the corners of the frames, which project at an angle due to their folded design. This lends the towers the symbolic character desired by Perrault that makes them the shining landmark – indeed, the CityLights – at the entrance to Boulogne-Billancourt. The folded frames split the LED light in a variety of directions in the night and reflect the colors of the sun and sky during the day. Through this effect, Perrault allows the architecture to visually merge into its surroundings. In order to also free the complex from its isolation in everyday life and create a lively meeting point for people who work here and residents alike, Perrault replaced the old center with a new, significantly larger entrance area. He named this 5 000-square meter heart of the building complex Agora, after the central festival and meeting places of antiquity. This area links two shops, five different restaurants, a children’s daycare facility and a fitness studio as well as a visitors’ lobby and a reception. The new, three-level underground parking garage can also be reached via the agora.

Lively exchange
The main entrance to this central connecting structure is marked by a diamond-shaped canopy made of high-gloss polished stainless steel that projects a great distance from the north-western side. This roof continues into the lobby, enabling its glossy underside to transport the daylight into the building interior. Furthermore, the tree-style, ceiling-high lights, each of which carries several spotlights encased in stainless steel on its branches, set additional lighting accents. Ten ceiling-high room dividers made of stainless steel mesh structure the visual openness of the 1 500-square meter room. In interplay with light, the woven structure softens the enormous dimensions of the space in an almost playful manner. Depending on the viewing angle and the angle from which the light approaches, the puristic panels can be both transparent and opaque. Their spiral mesh adds a dynamic nature to the entire room thanks to the reflections in the curved, seven-millimeter-thick stainless steel strips. As such, the panels, which are up to six meters wide and 9.5 meters long, are in permanent exchange with the highly frequented surroundings – whether as a backdrop or as a main protagonist. Perrault has already employed this effect in many of his successful projects. In the foyer of CityLights he combines the special appearance of the spiral mesh with its function as discreet screening (Escale 7×1) or fall guard protection (Escale 7×2). Unobtrusively shimmering mesh panels therefore also flank the broad stairwells, which lead to the two other levels of the foyer. On the plateaus these then form corridors that guide the visitors to their various goals. In light of the high numbers of visitors in the foyer, the stainless steel mesh was not only chosen for its aesthetics and functionality, but also its proven characteristics such as freedom from maintenance, robustness and non-combustibility. As an ingenious contrast to the textile structure, Gaëlle Lauriot-Prévost designed glossy ceiling lights shaped as stylized birds made of stainless steel. The arrangement of this light installation, named Albatros, is reminiscent of an enormous mobile, with the floating birds reflecting the light and entering into a lively dialog with the woven walls. Thanks to this holistic concept of permanent exchange between the architecture and its environment, Perrault created a state-of-the-art office complex that carefully took up the design concept of the ageing landmark and gave it a new lease of life.

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