Biosphere2 and Pima Air & Space Museum

Biosphere2 is a unique facility for environmental research that contains recreations of five of the Earth's biomes.

The Pima Air & Space Museum is one of the largest air and space museums in the world, and the largest non-government funded aviation museum. You'll see more than 300 aircraft and spacecraft including many of the most historically significant and technically advanced craft ever produced, both from the United States and throughout the world.  Unfortunately, I ran out of time and was unable to take the bus tour of the “Boneyard” at the Davis-Monthan Air Force Base.  I will have to catch it on my next trip to Tucson.