Arizona's 25 Must-Visit Attractions

25 Rediscover Biosphere 2

Are you visiting Tucson? Take a detour to Biosphere 2, a controversial space colony experiment in the 1990s. Glass domes and pyramids housed six ecosystems, including a rainforest, desert, savannah, mangrove, ocean, and an urban environment. You can check out the self-sustaining residence where eight individuals lived for two years without leaving. Today, Biosphere 2 is used by the University of Arizona for earth science and climate change research.