A site to see: The sun sets on Arcosanti in the late 1970s. Credit: Ivan Pintar

Atop a mesa in the high desert of central Arizona sit the dozen concrete structures of Arcosanti, the model city conceived by the Italian-born architect Paolo Soleri as an "urban laboratory" for experiments in sustainable living. Founded in 1970, this homespun precursor to Masdar, the much larger project now under construction in another desert halfway around the globe (see "A Zero-Emissions City in the Desert"), was an early attempt to combine innovative architecture with the clean technologies then at hand to conserve energy and minimize waste. It was to be a demonstration of Soleri's vision for how society could lessen its destructive impact on the environment.

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