On September 25th, 1991, 2,000 people gathered in the Arizona desert for a dance party.

With stilt walkers, with fireworks, it was a great dance troupe, Harlem.

We had part of the cast of Cheers, that TV program, the Boston Bar.

For Mark Nelson, it was a big night.

And not just because he got to party with Woody Harrelson.

This would be his last outing for a very long time.

What are you feeling?

Are you feeling anxious at all about the next morning?

Yeah.

Well, I think more excited than anxious. I mean, to me it was, you know, there was no way that this thing would fail.

This thing that could not fail? Biosphere 2, a nearly airtight glass complex in the foothills of the Santa Catalina Mountains, about an hour north of Tucson.

The next morning, Mark and seven others would go inside, and if all went according to plan, they wouldn't come out for

another two years. I'm Ella Fetter, and this is Atlas Obscura, a celebration of the world's

strange, incredible, and wondrous places. In the fall of 1991, eight people embarked on an epic experiment.

For two years, a small crew would live inside Biosphere 2 in Arizona,

along with thousands of carefully selected species,

kind of like a Noah's Ark on dry land.

And if all went well, Biosphere 2 could be an idyllic home.

A three-acre glass palace teeming with life,

where they would tend to a small rainforest,

grow fresh fruit on their organic farm,

and snorkel among tropical fish in their mini rectangular ocean.

...