The “Souterraine”, as the vault is known, was designed to withstand all attacks, according to the bank’s website.
The main shaft is protected by a 50cm-thick, seven-tonne door made of flame-resistant concrete and reinforced with steel.
Behind this door is a 35-tonne rotating concrete turret, which the bank says “prevents any possibility of forced entry”.
Last Sunday, masked thieves used an angle grinder to smash through a reinforced window into the Louvre’s Gallery of Apollo, where France’s crown jewels are kept.
Within eight minutes, the gang seized treasures, including a necklace that belonged to Napoleon’s wife Empress Marie-Louise and a diadem of Napoleon III’s wife Empress Eugenie, worth €88m (£77m).
The thieves used a mechanical ladder on the back of a lorry to lift them to a first-floor balcony to gain entry to the gallery.
