Biosphere 2 is out in the middle of nowhere Arizona - about 1 hour outside of Tuscon - but is worth the visit.
I guess I expected an actual sphere, but what you see in the picture is the glass enclosed mini-earth. The glass pyramid structure is home to the climatically different eco-zones. The white structure in the middle was the home to the "biospherians" for the two years they lived in the enclosure. The dome structure to the far right is one of the buildings two "lungs" that maintained consistent pressure in the whole structure - preventing it from collapsing in on itself.
The Biosphere is currently being used by the University of Arizona for research, but at the time of occupation had livestock, rice patties and even a Caribbean ocean. As you walk from zone to zone you won't believe that this was built for only 150 million.
The Public Guided Tour is a comprehensive, 45 min walking tour. It includes a video about the biosphere and its inhabitants, both plant and animal, and then a compound walk through. After the tour you can walk through the living quarters -which are 90's fabulous and wonder how the six individuals managed to eat only what they grew for two years. There is also an underwater viewing area you can explore on your own, although since cleaning the glass is against their "natural" policy there is not very much to see. Admission is a steep $20, but they do offer a military discount (along with several other discounts.) Jeff loved the engineering portions of the tour - and we can't stop talking about the lung design. I loved hearing about the drama surrounding the biospherians - including a pizza delivery to the compound and one of the woman leaving for a medical emergency. (Don't worry she was fine!)
I really cannot put into words how cool and weird this place is. You certainly don't need to come here more then once - and its starting to fall into a bit of disrepair - but if you remember reading about this at all in your science class, have some free time and find yourself just outside Tuscon it is worth checking out. Oh! Make sure to pack your lunch because although the Biospherians may have gotten Pizza delivered there are not many food options nearby.
Here is one final picture from inside the Biosphere: