Biosphere 2

 
Biosphere 1 is our earth. Biosphere 2 was built in 1980's as a miniature of earth to learn more about our earth and the environment. It's the largest greenhouse in the world and cost $150 million of private funds to build. The tubular metal frame in the pyramidal shape, and miles of underground pipes, the power plant etc. are an engineering marvel. Tours go through every day. We visited last Sunday after a rare snowstorm on Saturday night. It was beautiful - 4 inches of snow at 4000 ft !