Take a look inside the global seed vault in this clip from National Geographic's upcoming 3-night special, "How The Earth Changed History".

The seed vault, built to protect the world's food supply in the event of a global crisis, is located on a remote Norwegian island in the Arctic Svalbard archipelago. It was built high enough to avoid rising sea levels, and deep enough into the mountain to be able to withstand a nuclear explosion. The vault is kept at a constant temperature of zero degrees to preserve its contents.

"How The Earth Changed History" premieres Sunday, June 20.