In the heart of Monaco’s coastline, a new vision of urban development has come to life. Dubbed the Mareterra project, this floating eco-district was officially completed this month, setting an unprecedented global benchmark. Built entirely on "land" reclaimed from the sea to create new territory for development, this urban expansion adds six hectares (about 15 acres or 3% of Monaco’s total land area), seamlessly blending environmental stewardship with architectural sophistication.
"I wanted this new area to embody the excellence and conviviality which distinguish the Principality of Monaco so well," says HSH Prince Albert II of Monaco. "Mareterra will integrate perfectly with our shoreline, and in a few years will be seen as a natural extension of our territory."
The project was developed via a collaboration between Renzo Piano Building Workshop (RPBW), Valode et Pistre Architectes, and landscape architect Michel Desvigne. The district – which includes the Le Renzo residential complex, public parks, a marina, and commercial spaces – prioritizes public access, with half of the area dedicated to parks and leisure spaces.
A key feature of Mareterra is its construction on water. The project expands Monaco’s coastline using underwater caissons (large concrete boxes) which not only provide land space but also serve as marine habitats to support biodiversity. This engineering method was specifically developed in consultation with marine biologists to minimize ecological disruption. Additionally, measures were taken to relocate and monitor native species like Posidonia seagrass and red coral. Anti-turbidity screens were also installed to protect nearby marine reserves.
In line with Monaco’s carbon neutrality goals for 2050, the project integrates several energy-efficient systems. Solar panels supply 40% of the district’s energy, and a seawater thalasso-thermal loop provides heating and cooling, reducing energy consumption. Rainwater is harvested for irrigation, plus green roofs (along with over 1,000 trees) help mitigate urban heat. Notably, a 1-hectare (2.47-acre) pine forest has been established, offering both environmental and recreational benefits to residents.
Mareterra’s sustainability efforts are underscored by several certifications, including BREEAM "Excellent," HQE Aménagement, BiodiverCity, Espace Vert Écologique, and European Clean Ports.
Mareterra also enhances Monaco’s cultural infrastructure. The Grimaldi Forum has expanded by 10,000 square meters (107,640 sq ft), with 6,000 square meters (64,583 sq ft) dedicated to exhibition space, providing venues for cultural events. The district also features restored artworks, such as Alexander Calder’s "Quatre Lances" in Princess Gabriella Square, and a “Meditation Space” designed by Tia-Thủy Nguyễn.
A pedestrianized promenade connects various parts of the district, offering scenic views of the sea while linking residential, commercial, and recreational areas. Visitors can also explore The Blue Grotto, an underwater viewing area showcasing marine life thriving within the caissons.
The €2 billion (about US$2.08 billion) Mareterra project stands as a global engineering and environmental milestone, with over 300 companies and workers from more than 40 nationalities contributing to its construction. This international collaboration highlights its innovative approach to sustainable urban planning. It is not just an addition to Monaco’s land but a forward-looking vision for the future of coastal cities.
Source: Mareterra
