Inside Mareterra, Monaco’s €2bn neighbourhood built on reclaimed sea
Eight years ago, the ground beneath Mareterra was open sea. Today, Monaco’s newest district is a bustling stretch of restaurants, offices and apartments connected by Promenade Prince Jacques, an 800m waterfront walkway where joggers and parents with strollers now share space with diners at Marlow, the principality’s first British fine-dining restaurant.
Unveiled in December 2024 at a cost of €2bn, Mareterra is Monaco’s latest response to a problem it has faced for over 150 years: how to grow when there is no land left to grow into. The world’s second-smallest country after the Vatican packs roughly 38,000 residents into just over 2 sq km, making it the most densely populated nation on Earth despite its wealth.
Monaco’s answer has long been to push outward into the Mediterranean. Since 1907, land reclamation has expanded its territory by a quarter, creating areas including the Larvotto beachfront, the Port Hercules marina and the Fontvieille district. Mareterra continues that tradition: Prince Albert II announced the project in 2013, reclaiming six hectares near Larvotto and adding 3% to the principality’s total land area. The new district includes two residential blocks — one designed by architect Renzo Piano — plus 10 villas, four townhouses, a marina, 14 commercial units and three hectares of public space.
Engineering the seafront
The neighbourhood sits on 18 giant concrete caissons, each weighing 10,000 tonnes and standing 26m high, arranged along the seafloor like building blocks. Their upper sections, known as Jarlan chambers, let water flow through narrow vertical openings designed to absorb and break up wave energy. “That means, even during 100-year storms, they won’t rise too high nor submerge [Mareterra],” said Guy Thomas Levy-Soussan, managing director of developer SAM L’Anse du Portier, inside one hollow chamber nicknamed La Grotte Bleue.
Building the caissons also meant addressing the marine life the project displaced. Grooves and textured surfaces were built into the concrete to attract fish and other sea creatures, while one of the most delicate tasks involved relocating 384 sq m of Posidonia oceanica, a protected seagrass crucial to the Mediterranean ecosystem. Using a modified tree spade, engineers transplanted whole sections of the plant along with their root systems to a protected area 200m away. “Usually we transport Posidonia plants one by one,” said Sylvie Gobert, an oceanologist at the University of Liège who worked on the project. “What is ultimately innovative is that we took the Posidonia, along with its entire root ecosystem and about a cubic metre of sediment.”
In keeping with Monaco’s target of carbon neutrality by 2050, Mareterra was built with sustainability in mind, incorporating 9,000 sq m of solar panels, 200 EV charging points and 800 trees. The district also expanded neighbouring attractions, including the Grimaldi Forum event space and the Japanese Garden, and added quieter spaces such as a small woodland walk and a public square built around Quatre Lances, a sculpture by Alexander Calder once owned by Grace Kelly.
Yet the project isn’t without critics. Despite being promoted partly as a response to Monaco’s housing pressures, apartments in Mareterra are reported to start at around €100,000 per square metre — among the priciest real estate anywhere — and none of the new homes have been set aside for Monegasque citizens, who are otherwise entitled to subsidised housing.
Even so, those close to the project doubt Mareterra will be Monaco’s last expansion. “For Prince Albert, if there isn’t construction, the country is at a standstill,” said Nancy Heslin, co-founder of Carob Tree Publishing, who has interviewed the prince. Levy-Soussan agrees the principality will keep pushing its boundaries “on both a technological and ecological scale,” adding: “Monaco is a small country that has done extraordinary things.”
Source: BBC News