Our first stop on a Southwest road trip was Paradise Valley, Arizona, where we toured a historic compound built in the 1950s by Italian architect Paolo Soleri. He experimented with earth-casting techniques to create habitable structures formed with a concrete shell over mounds of earth. The soil beneath the shell was then excavated out by hand and what remained became the walls and roof. His architectural philosophy of "arcology" is a blend of architecture and ecology. The unique structures incorporate passive solar heating and cooling, and were built for living more fully and sustainably. The compound is still being used to house and train students of architecture and is the site of a foundry that produces bronze and ceramic wind bells.