See inside the 'doomsday' seed vault, where billions of seeds are stored in case of nuclear war

Eight-hundred miles from the North Pole, on the remote island of Spitsbergen, a huge vault sits 130 metres inside a cavernous sandstone mountain.

Behind the thick concrete wall lies the most diverse selection of food crop seeds in the world. Seeds from almost every country line the shelves as an emergency food supply to be used only in the event of nuclear fallout, mass famine, or other global crises.

The first withdrawal from the "doomsday" vault was made this year in a big to restore ancient crops wiped out by the Syrian civil war.

Its location and unique construction mean that this vault is the ultimate safeguard for the world's food supply.