The world’s second-smallest sovereign state has recently grown by 3% thanks to an innovative new initiative. The Mareterra eco-district, as the neighbourhood is called, has been built into the Mediterranean Sea, thus answering to the country’s lack of space.
With a population of approximately 39,000 people, at first sight, Monaco doesn’t seem to have any overpopulation issues. However, knowing that the entire country measures 2.08 square kilometres, it is not difficult to see why the state is looking for some extra space to expand. Especially since almost seven out of ten of its residents are millionaires, according to property firm Knight Frank.
The new Mareterra project partially resolves that problem. The so-called eco-district, which cost $2 billion, is a luxury development including a marina, seaside promenade, and high-end housing. Its particularity consists of the fact that it is entirely built into the Mediterranean Sea, meaning the state gained some 3% of the land surface when the district opened its doors at the end of 2024. Half of that surface is accessible to the public, offering a park, cycling paths, a marina and shopping facilities. 800 trees were imported from Tuscany in Italy to offer some much-needed greenery, helping to make the pedestrian neighbourhood feel like a village, albeit a very modern one.
“Mareterra is a largely pedestrianised district that encompasses a lushly planted park, an elegant waterfront promenade, a small port, underground parking and both residential and retail offerings. The master plan has been carefully conceived to integrate with the existing coastline and provides important new recreational and cultural opportunities for the people of Monaco. With its distinctive curved coastline, gently rising hillside, and native flora, Mareterra forms a vital new waterfront connection for the people of Monaco, from Port Hercule to Larvotto beach,” the developers explain.
Mareterra was first announced in 2013 and is quite the engineering marvel. In order to make the project possible, concrete chambers were constructed in the sea, which were then drained of water and filled with 750,000 metric tons of sand.
Once the groundworks were done, the privately funded project could really take off. The neighbourhood includes approximately 100 apartments, 10 villas, four townhouses and 14 commercial spaces, for which high-profile architects provided the designs. Norman Foster and Tadao Ando were some of those working on Mareterra, while Renzo Piano – who also designed the Centre Pompidou in Paris – even lent his name to a residential building called ‘Le Renzo’ designed by his firm.
According to Knight Frank, people can expect to pay some €100,000 per square meter for a Mareterra property. Monaco’s government receives a 20% tax on all property sales and thus benefits from the privately funded project. None of the housing units at Mareterra have been reserved for some of the 10,000 Monegasques who are entitled to subsidised housing.
Monaco’s expansions
While building into the sea might sound like something extraordinary – which it is – it is not the first time Monaco has expanded its surface by reclaiming the sea surface and turning it into building grounds. Approximately a quarter of the country’s territory consists of such ‘reclaimed’ land. The most important land reclamation happened during the 1960s and 1970s when the Larvotto and Fontvieille districts were built, but the first reclamation even dates back to 1907.
Such projects have raised environmental questions in the past as Monaco’s marine life is naturally impacted by land reclamation. In 2009, another project was refused, partly because of ecological concerns raised by Monaco’s Prince Albert II.
Mareterra’s ecological measures
During the development of Mareterra, various initiatives were taken in dialogue with marine experts in order to limit its environmental impact. Reliefs and grooves were carved into the concrete chambers under the district in order to attract marine flora and fauna. The so-called Jarlan chambers provide shallow areas, much-loved by fish. Moreover, 510 square meters of Posidonia oceanica – a species of protected sea grass crucial for the Mediterranean ecosystem – were saved and replanted in the Larvotto Marie Protected Area nearby.
“Usually we transport Posidonia plants one by one. What is ultimately innovative is that we took the Posidonia, along with its entire root ecosystem and about a cubic metre of sediment,” Sylvie Gobert, an oceanologist at the University of Liège in Belgium who worked on the project, told BBC.
Moreover, sustainable technologies were used during the project in order to limit its ecological footprint and thus align with Prince Albert II’s commitment to make the principality carbon neutral by 2050. For example, 80% of the district’s heating and cooling will be provided through renewable energy, provided by geothermal heating on seawater. 9,000 square meters of solar panels provide electricity, an irrigation sprinkler system based on humidity and rainfall limits water consumption and 200 charging systems for electric vehicles are present on-site.
