The atoplanes were capable of indefinite flight, and the swiftest of them could go two thousand miles an hour. Gargantuan atoliners made daily roundtrips from both Europe and America. Ships had practically vanished from the seas, and railroads from the land. Atomobiles, Speeding along hard-surfaced roads that radiated everywhere, transported passengers and some of the lighter freight. Most of the passenger travel, however, was in small, privately owned atoplanes which had a speed of about five hundred miles an hour. Every city had its atofield, and many of the older houses and nearly all of the office and industrial buildings had been covered with flat-topped structures affording landing stages, while all of the new buildings were being constructed on this plan. Elevators, opening on the roofs, provided descent into the structures. Equipped with super-helicopters, the machines needed only their own displacement in which to land or rise. Atoheat supplied warmth in all buildings, while all but the smaller dwellings used atolight for illumination.