In the time-scale of human history we have only just realized that air has substance and predictable properties. In the last 50 years, this realization has enabled man almost to overcome distance by means of aircraft. In the next 50 years, we can almost overcome the vagaries of weather by placing an airsupported membrane between ourselves and the elements. The theory involved is simple; the problems lie in its application and in finding suitable materials for the membrane. However, just as the development of the aircraft industry fostered the production of aluminium, so the development of air structures will doubtless encourage the manufacture of translucent and reflective plastic membranes.