World's biggest doomsday vault has just been opened to reveal what's inside

If you had to bet where the world's biggest 'doomsday vault' was located you might not choose the UK, and you almost certainly wouldn't pick the ground beneath the Kew Gardens site at Wakehurst.

It's true though, if you take a trip there you won't be allowed in since public access to the underground facility is prohibited but the BBC's Noa Leach was allowed in for a visit and explained it's a high security location.

However, this place isn't designed to shelter humans in the event of a global catastrophe, as it's already full of the building blocks of another particularly precious form of life, seeds.

It's only natural that a giant underground vault located beneath a garden would be a storage site for seeds, and the Millennium Seed Bank holds the most seeds of any facility of its type around the world.

The Millennium Seed bank contains the world's biggest vault of seeds kept frozen and safe beneath the ground (Tim Graham/Getty Images)

Leach explained that there are more than 6.6 tonnes of seeds stored in the vault, with the exact number not known but there being many millions of some of the samples they have.

There are seeds large and small, some of the ones kept safe and sound belong to species of plant which are extinct in the wild while many others are endangered, which rather proves the need for places like the Millennium Seed Bank.

Leach explained that the seeds were kept in freezing conditions of -20°C and that security is automatically set off if someone spends more than 10 minutes inside the sealed vault.

That's not for fear that someone might break in and steal the seeds, though some are very valuable and desired by collectors, but instead to stop someone who goes inside from spending too long in the sub-zero temperatures and freezing to death, Leach even had to sign a waiver in the event that her heart stopped while inside.

The underground vault is built strong enough to surviving flooding, radiation and a direct aircraft hit so this ark of potential life is relatively safe from outside harm or someone attempting to sneak in.

This place could survive a direct hit from an aircraft, and the seeds inside are kept at freezing temperatures (BEN STANSALL/AFP via Getty Images)

Plus they don't label the containers so unless you can get someone inside both the vault itself and the computer system, you won't know what's what once you're in the exceptionally cold rooms.

While this is the biggest seed vault in the world designed to make sure that plant life can survive no matter what humans get up to, on the surface there are many more like it around the globe.

The Millennium Seed Bank has more seeds than anywhere else but there are over 1,700 seed banks including the underground bunker called the Global Seed Vault.

Built into the ice of the Svalbard archipelago, Norway, the Global Seed Vault houses over a million seed samples from all over the world.

Like the Millennium Seed Bank, you're not allowed into the place without a huge amount of security clearance, but you can take a virtual tour.