I remember the first Biosphere experiments and looking at photos of it in magazines. It has fascinated me ever since, so when I realized that it was just a bit out of our way on a road trip it became part of the plan. The two parts I found the most amazing were the crew quarters from the sealed live-in experiments and the "lung" that adjusts for the changes in pressure in the buildings. It was fun to see "love long and prosper" on one of the coveralls work by one of the 2 groups to live in the Biosphere. I wish that the talk and tour had discussed more about what happened with the live in experiments and what was learned and done as a result of them. However the University of Arizona owns it now so much of the talk was about the current experiments which is paying for the place I guess! It is a long walk so may be difficult for anyone with mobility issues and it gets really warm in some parts of the building like the rain forest, so wear layers!