Over the past 20 years, the Arenc district of Marseille has transformed from an industrial port hub into a vibrant cultural and commercial centre. This is in large part due to the Euroméditerranée development, a 480-hectare business district (the third largest in France), which saw the Docks de Marseille converted to office spaces and the Silo, a former industrial building, reimagined as a performance hall.  Ever since, the area has become an architectural hotbed: Zaha Hadid completed the CGM Tower in 2011, while the Tour La Marseillaise, designed by Jean Nouvel, opened in 2018. La Porte Bleue, a dynamic new mixed-use tower designed by Paris firm PietriArchitectes, is the district’s latest architectural marvel.

Its site imposed a challenge: The building was to be erected atop a previously built underground parking lot. Originally, the plot was supposed to accommodate two towers, but due to its irregular shape, the architects opted for a singular tower to make better use of the space. Located just next to the Tour La Marseillaise, La Porte Bleue also sits at the intersection of the highway that leads in and out of the city, and the port, which is a revolving door of passengers and cargo. As a result, the building was conceived as a gateway to the city.

When seen from the highway, it makes a strong first impression. Comprised of a series of Mediterrannean-inspired vaulted arches, the low-carbon concrete façade boasts a graphic quality that immediately draws the eye. While it was designed by architect Jean-Baptiste Pietri to reflect the heritage of the city (which was founded by Greek settlers in 600 BC), the stark white colour feels decidedly contemporary, selected by Pietri in reference to the colour of limestone. The material, meanwhile, was selected for its strength and durability, allowing the vaults to be as thin as possible while combatting corrosion, a major concern given the building’s proximity to the sea.

PietriArchitectes worked with structure and façade design experts at Atelier Masse to develop the complex envelope. Though, from a distance, it reads as monolith, the façade is actually comprised of 414 Y-shaped modules (in 13 different variations, including double-height) manufactured off-site in the town of Aubagne, and then placed one by one using a crane. Each 90 centimetre-thick vault is linked to the cast beams and slabs to become self-supporting. Given their depth, they also help to protect residents from the wind and sun.

The building’s monolithic quality belies its programmatic variety. The 53-metre-tall tower comprises a four-star hotel on the 11 lower levels and 68 residential suites across the upper seven levels. While on the lower floors, the interior volumes correspond to the rectilinear grid of the parking lot below, the architects broke away from this pattern when designing the private residences. Inside, the façade’s repeating archways softly frame sweeping views of the sea to the west, and the city to the east and south. Each unit also features a large loggia that acts as an open-air living room.

On the ground floor, a series of retail spaces faces the Docks de Marseille, while a restaurant projects outward from the main volume, welcoming in the public. The ambitious project, like many others in the Euroméditerranée district, is connected to the Thessalia marine geothermal energy plant, which allows the building to be heated and air-conditioned with clean energy.

While La Porte Bleue’s façade is sure to become an icon of the Marseille skyline, its beauty lies not only in its aesthetic but also in its symbolism. As a port city, Marseille has become a melting pot of cultures, having welcomed newcomers from Europe, Asia and the MENA region since the 18^th century. “Through its vaults which lean on each other, like so many elements that make up a puzzle and which could not exist without each other, The Porte Bleue appears as a true homage to the roots of the city,” the designers explain.