Robert Vicino thinks humans are living in what is sometimes called “the end times.” He believes that a natural or manmade disaster will soon make life on the surface of the Earth impossible.

His company -- called “Vivos” -- is building what it says is the world’s largest private underground survival shelter.

This artist rendering released by Vivos, an underground shelter network, shows a design for an underground bunker.

Mr. Vicino says he felt the urge to build the shelter more than 30 years ago.

“Somehow, I had this inspiration that I needed to build a shelter deep underground for as many as 5,000 people for what is coming our way. And the key word there is ‘coming,’ and the question is ‘from where and what?’ I didn’t know the answer. I still don’t.”

Paved roadways lead the way to the Vivos Shelter and Resort during a tour of the facility in Atchison, Kansas, June 18, 2013.

The shelter will be built in the mid-western American town of Atchison, Kansas, 40 meters below a limestone mountain, in a place that was once used by the Army to store weapons.

Only people who pay the one-time cost of $20,000 can use it. Anyone in the world can join.

Paul Seyfried is an adviser to a group called the American Civil Defense Association. It tries to prepare the public for manmade and natural disasters. Mr. Seyfried wonders if the Vivos shelter could operate if a disaster hits.