The domed structure is one of the earliest forms of shelter–from African mud huts to frozen igloos to holy shrines and cathedrals. As a design concept, the shape represents the community under the canopy of heaven; as a technological device, the dome is the most efficient way of controlling an internal environment. And today, as we see here, engineers have enlarged and transformed the ancient concept to build some of the world’s most spectacular structures–domed sports stadiums.