The main idea of the Riparian Forest of the Athletes’ Village was inspired by Floating Island, a work by Robert Smithson from 1970, never realized during the artist’s lifetime. The project was recently brought to life by the American landscape architecture firm Balmori. Floating Island is an industrial barge transporting a piece of what was supposed to represent the native landscape of Manhattan Island, prior to the dramatic growth of the New York City megapolis. The idea also fit within the urban concept of the neighborhood designed by Dominique Perrault, who imagined the new buildings as huge cargo ships—building vessels docking along the quays of the Seine. We imagined the garden as a fragment of riparian forest, typical of the fresh riverbanks of the Seine, which once covered the site of the Athletes’ Village. Our ambition was to recreate the entire ecosystem with its indigenous association of flora and fauna. A forest-garden that arrives among the buildings on an imaginary barge and is then left to evolve freely, guided by the dynamics of nature. The idea itself is simple, but making it real was a long journey.
For centuries, the site was occupied by heavy industrial activity. The original soil was therefore degraded and partially polluted. In addition, the geography of the entire neighborhood had been radically transformed by the urban project. Hence, the first task was to create the fertile base for the future landscape. We worked closely with UAPS (the chief architect-urbanist of the surrounding buildings) to avoid, as much as possible, any underground construction in the central part. As a result, all parking is located beneath the buildings, except for a single connecting driveway between the two main wings. We then teamed up with the structural engineers to ensure they accounted for the weight of approximately 120 cm of soil above the first building level hosting the community terraces, and 50 cm on the rooftops carrying the wild grasslands.
Rather than importing thousands of cubic meters of garden soil, we chose to work with anthroposols. Inspired by the natural processes of soil formation, this technique uses infertile and otherwise unusable landfill to create a new fertile substrate. By avoiding the use of natural resources and recycling earthwork waste, this process saves tons of CO₂ compared to traditional methods. The mixture was prepared off-site and regularly monitored during its six-month maturation cycle, during which it was seeded to develop a protective prairie planting that fostered microbiological life, added organic material, and limited the spread of invasive weeds. Following the natural scheme of woodland soil layering, we developed three distinct horizons:
• The first, the topsoil, has the highest percentage of organic matter and is where roots draw most of their nutrients.
• The second layer is designed as an anchor for the root system, with less organic material but providing stability.
• The third layer has coarser granulates to promote drainage.
The overall depth of this profile is about 150 cm in the central garden (which is in full ground with various fillings underneath), 120 cm on the community terrace level, and 50 cm on the rooftops. The thickness of each horizon varies depending on the context. The engineered soils were delivered to the site by boat—a sustainable transportation method that halved CO₂ emissions and also served as a poetic reference to the project’s inspiration.
The next step was to design the topography. We aimed to create a garden with a rich mosaic of biotopes, united in a single landscape. In nature, variations in topography result in different levels of soil hygrometry, which encourages the establishment of varied plant communities. The central part—about 20 meters wide and 180 meters long—is in full ground and also functions as a sponge, draining all the rainwater that falls on the buildings. Excess rainwater collected from the rooftop gardens arrives in the central forest via above-ground gargoyles and irrigates the forest-garden. Since the ground profile is carefully sculpted, the patchwork of swales retains and infiltrates runoff, while excess water is directed toward the main wetland meadow on the Seine side of the project. The site’s water absorption capacity was carefully analyzed by the design team’s engineers, and the volume of the hollows for temporary retention was precisely calculated. The result is a rolling landscape, forming a micro-topography that looks as if it had been shaped by the natural dynamics of rainwater runoff. Limestone rocks add to the landscape, creating habitats for small mammals and reptiles. Thanks to the generous layering of soil and the recycling of rainwater at every level, the entire project—rooftops included—functions without any artificial irrigation system.
Once the questions of soil, topography, and water resources were resolved, we took a closer look at the plant palette. The entire garden is inspired by the riparian forests that follow the curves of the Seine all the way to the ocean. But recreating the exact indigenous composition was unrealistic on a site that never floods and is partially not in open ground, as in the case of the rooftops. Therefore, the project concentrates the densest vegetation and highest tree canopy in its center, where roots can spread freely below ground. The community terraces overlooking the central forest from the first floor were planted as forest edges, mainly with shrubs and small trees, while the rooftops on the 6th and 7th levels are planted exclusively with grassland species. Most of the plants are indigenous and locally sourced and grown (under the “Végétal Local” label). This is essential to preserve the genetic heritage and memory of local flora. To create a more resilient plant composition in the face of climate change and its unpredictable heatwaves and droughts, a smaller portion of the species comes from the southern regions of France (Ficus carica, Cercis siliquastrum, Quercus cerris, Quercus pubescens, etc.).
The project uses mostly recycled or upcycled materials. In addition to the engineered soils, both the structure and surface of the pathways (all 100% accessible to PRM) are made of recycled gravel. The benches are crafted from upcycled, untreated tropical wood reclaimed from old mooring piles in European ports. The brick paving was produced from local resources by a family-owned brickyard in Normandy. The oak used for the terraces and pedestrian bridge comes from closely monitored French forests. The entire project aspires to deliver a strong message of absolute respect and admiration for nature, which society urgently needs to reconnect with.
The project’s graphic design explores the sinuous forms of a natural riverscape. The pedestrian bridge connecting the central garden to the belvedere terrace overlooking the Seine follows the same curves as the paths. The scenery shifts dramatically when the visitor moves from under the riparian forest to the main meadow, crossing the footbridge that weaves among the crowns of birches and alders. The view of the meadow from above is one of the highlights of the walk, just before the panorama of the Seine.
As for the uses, the central part functions as a sort of “sanctuary”. It is reserved for calm activities such as walking, reading, and observing. The community gardens on the first level are the neighborhood’s lively hubs, with picnic areas, vegetable plots, a small playground, lounge chairs, etc. This is where social connections among residents were built. The rooftops are inaccessible and reserved for migratory birds. They provide crucial, undisturbed resting spots along their journey along the Seine.
The humble idea of the project is to provide a first impulse for a natural forest-garden. From there, the riparian forest of the Athletes will evolve on its own, depending on each species’ ability to adapt to natural dynamics. The ever-changing appearance of this free forest-garden will shift with the seasons and the years. Some species will disappear, giving way to others to grow, and the Unit D gardens are intended to serve as an open-air laboratory for plant succession. But to let the magic happen, maintenance is key. TN+ developed a complete monthly maintenance guide. For the first three years, the company that built the garden will take care of it. Their teams have been trained in the specific maintenance required, and the forest is currently expanding—especially after the exceptionally rainy year of 2024. The prairie is selectively mowed only three times per year at first (and twice later on). In areas where new perennial or shrub vegetation appears spontaneously, mowing is skipped if the spot seems promising. The maintenance crew must be able to recognize young trees and shrubs in the tall grasses and avoid cutting them. At the same time, full canopy coverage is not desirable, as it would reduce ecological diversity. Clearings are therefore mowed regularly to keep some vegetation low and allow sunlight to reach the understory.
It’s all about a subtle sensitivity to vegetation—one that isn’t always easy to develop but brings great satisfaction once acquired. Since the goal is to accompany and support the growth of the forest-garden, rather than control or fix it, this approach offers a meaningful way to reconnect with the harmony of nature and to learn from it.
Now that the Olympics are over, the village is beginning its transformation into a new neighborhood. Once the three-year maintenance period ends, we will help the future residents’ association understand how to embrace the natural “disorder” of their riparian forest—and how to keep the magic alive.
• All landscape architecture offices involved in the design of landscape:
TN+ landscape architects / Team leader, Conception, Construction Supervision
• Other credits:
EGIS & BERIM / Civil Engineer
OASSIIS / Environmental Engineer
