Ex U-Boot-Bunker Martha, World War II naval bunker in Marseille, France
The ex U-Boot-Bunker Martha is a massive concrete structure in Marseille built during World War II to shelter German submarines. It stretches about 208 meters long and 45 meters wide, with 13 docks designed to protect the vessels inside.
The bunker began construction under German occupation as part of a strategic Mediterranean naval base. Allied bombing raids in December 1943 caused substantial damage to the still-unfinished structure.
The structure stands as a testament to wartime engineering and now functions as a modern data center, bridging military history with technological advancement.
The site is difficult to access today and functions as a data center, making tours generally unavailable to the public. However, you can view the exterior from nearby and appreciate the scale of this wartime construction from outside.
The structure was originally connected to the harbor through water channels, but harbor expansion over decades has now completely isolated it from the Mediterranean. Today it stands like a relic from another era, surrounded by modern port facilities and industrial development.
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