World War-II Submarine Base Transforms Into Data Center

Marseille, A Global Connectivity Hub

Marseille is truly a global city, with its geographic positioning making it a strategic platform, as well as a migrating and cultural crossroads. European capital for culture in 2013, sixth European freight port, ranked by the Organization for Economic Co-operation and Development (OECD) among the most dynamics metropolis in Europe, Marseille has made the most of its assets to foster its development and become the economic and cultural capital of the Mediterranean. 

Marseille is not only the gateway to Europe with robust connectivity to FLAP Ð Frankfurt, London, Amsterdam, Paris Ð all of which are major Internet Infrastructure markets, but with over 20,000 kms of subsea cables, Marseille is the connectivity gateway between Europe, Africa, Middle East and Asia. Marseille has connectivity to countries as far east as Singapore, China and India. Today, Marseille is also a telecom, cloud and digital gateway between Europe, Africa, the Middle East and Asia. The organization of several events of the 2024 Olympic Games is a real opportunity for Marseille to reinforce its role in content distribution.

Historically, Marseille has been a key location for exchange, previously for goods and freight and now for data. In 2015, the value of data exchanged throughout the world exceeded the value of goods and freight. Marseille is a global strategic hub for data exchange, with the presence of 14 submarine telecommunications cables, and several cable projects underway.

The “Subsea Effect” has led all major cloud providers, content providers and Content Distribution Networks (CDNs) to be located in Marseille. Additionally, there are five Internet Exchange Points (IXPs) in Marseille for peering of IP traffic.

Marseille, A Subsea Cable Friendly City

Marseille is a role model when it comes to subsea cable landing, thanks to the solution developed by the Port of Marseille. The existing (14) subsea cables land in Prado Beach, Bonneveine and Point Rouge, with several CLS serving the cables, including Verizon Bauxite CLS, Orange St Mauront CLS and Orange Bonneveine CLS.

The Port of Marseille has recently completed a project wherein they have proactively deployed 4 x bore piles, installed a new beach manhole (BMH) and subsequent landing manholes, and PFE shelters. This infrastructure will further help in landing additional subsea cables in Marseille. The port has also established anchor- and fishing-free zones for protection of subsea cables.

Consortium’s operators who would need to connect to data center facilities have the possibility to connect to the data center they want. Close to the Port of Marseille solution, they can choose to connect to Interxion’s existing MRS1 and MRS2, which are tethered together and have abundant conduits and fiber connectivity between the sites. MRS1 and MRS2 have over +10,000 sqm of equipped space with 124 million euros of investment made. The MRS2 provides subsea operators a diverse data center option to MRS1, which is where the majority of subsea cables terminate and distribute capacity.

MRS3, which is currently under construction, will be Interxion’s third data center and will have connectivity to MRS2 and MRS1. MRS3 is being built primarily to serve hyperscale customers and has some very unique elements. It took Interxion’s in-house engineering department nearly six months to confirm the feasibility of the project to transform “Martha” a former submarine base built by Germany during the Second World War, into a 21st-century data center.

World War-II Submarine Base Transforms Into Data Center

MRS3 used to be a World War-II submarine building facility “Martha” that was abandoned by the Germans, and you can feel its robustness as you set sight on it. The facility is situated in the heart of the Marseille Port area and is built of solid concrete, using railway sleepers as steel reinforcement. With walls as thick as 5.5 meters of reinforced concrete, the building has 5.5 meters thick concrete ceilings. Originally built by the Germans near the end of World War II, this U-boat bunker was never actually completed. A giant harborside concrete monolith, it sat vacant for more than 75 years, attracting graffiti artists and dust. We are now transforming it into a hyperscale data center.

MRS3 is being fitted out to be a hyperscale data center with 80 megawatts of critical power Ð enough to power 20,000 homes. We plan to make the facility the home of cloud and digital media companies. We are building in the necessary redundancies to support the world’s biggest cloud and digital media platforms in the electrical and mechanical infrastructure required. As for connectivity, all the carriers, IXPs, CDNs, SDN providers, content providers Ð basically our entire connectivity ecosystem that already exists in MRS1 and MRS2 Ð will be accessible seamlessly from MRS3.

We usually prefer to do greenfield data center builds, so this is a unique project for us. We are investing approximately 140 million euros (US$160 million) in the project, to take advantage of the scale, robustness and strategic location of this facility. Our approach is to build an expandable, modular data center facility. In order to attract major hyperscalers, having scalable and reliable power is extremely important. Our focus with MRS3 is to sustain high-capacity dense compute power deployments of servers. In essence, we are targeting to supporting cloud and digital media platforms at MRS3.


2015 was the first year during which the value of data exchanged throughout the world exceeded the value of goods and freight.

MRS1 & MRS2:

  • Over +10 000sqm of equipped space
  • 124 million euros of investment


  • 250-meter-long bunker covered by a 5.5-meter-thick concrete slab forming a terrace and connecting to a deep, canyon-like yard enclosed by a 12-meter-high wall
  • This concrete colossus had been abandoned for nearly 75 years
  • Historians have suggested that after the war, “Martha” might have been used as a prison for the Germans
  • It took Interxion’s in-house engineering department nearly six months to confirm the feasibility of the project to transform “Martha” a former submarine base built by Germany during the Second World War, into a 21st-century data center