Free Levels: The Host by Peter Emshwiller

bi-level.
    The development of the bi-level system was not a planned one, the stories said. No one ever sat down and designed it that way. It was never laid out on some blueprint. Referenda and polls and votes were never taken. No, Watly had heard that it grew all by itself. It evolved not long after Cedetime. There was some disagreement even among the historians Watly had read on keyboard, as to how it all got started. The general consensus attributed its inception to Walker Gavy, real estate baron.
    Mr. Gavy was a wheeler-dealer. They say he devoured plots of land like another person would eat a meal. Gobble, gobble. Each day enormous areas of the island country would change hands, and they almost always passed through Walker’s hands first. At one point he owned a large piece of prime real estate in mid-Manhattan. It was a Fifth Avenue section in the fifties, and full of very profitable retail businesses. He’d been holding on to it for some time. One day, one of his many lackeys made an off-the-wall suggestion. A crazy suggestion. Gavy liked it. He never turned down an idea that might yield a profit, and this idea sounded good to him. He began work on the project right away. The central concept amounted to nothing more than a glorified mall. It was a way to attract more businesses, more people, and—he hoped— more money.
    The idea was to build a second “street” five stories above the first. This higher street would be for pedestrians only and would be accessible through numerous elevators. New stores and other businesses could be put in up there. Where there once had been only windows and ornaments and ledges and air conditioners, Gavy would cut out doorways and install elaborate storefronts. So that the lower level wasn’t too dark, he designed the upper street with a center strip of clear glass to let sunlight down.
    They say his many critics had called the project absurd. Walker Gavy never denied it was absurd—not at all. The point was, he thought it would work anyway. And it did. After changing a few zoning laws, fighting a few noisy groups and associations, and greasing more than a few palms, Gavy built a small “sample area.” A couple of shops and restaurants, far above the madding crowd. Yes, it did work. It worked fabulously. People flocked to the area as much for the novelty of it as anything.
    An embryo had been conceived, or a fungus, or perhaps a cancer—depending on one’s viewpoint. Watly thought of it as a fungus. Whichever, the idea caught on and others tried it and added to it. It seemed a good investment to many, and so it continued. Second Level expanded. People hardly noticed any change, though it was not all that gradual. In just a few years, 25 to 28A.C. or so, large areas of the city became bi-leveled. It was unpopular among the rich and the powerful (usually one and the same) to live in the lower or “dark” level, as it was called. No matter how many glass panels or gratings in the upper level, the lower was still largely in shadow.
    As more and more of the city was covered, the technology involved progressed. The upper “streets” were reinforced and braced to handle private vehicles. A somewhat primitive (by modern standards) system of suspension support poles was set up. The idea of permitting sunlight to pass down to First Level became impractical and was abandoned. Artificial sunlight (daylite) was tested and eventually installed throughout the First Level. These lights supposedly mimicked exactly all healthful qualities of real sunshine, though Watly had his doubts. In addition, they were timed to three convenient brightnesses: bright for day, half power for evening, and low for night. All the comforts of Sol. The exhaust fans and intake ducts were added. Gradually, First Level was literally being sealed up tight.
    It became more and more difficult to travel from one level to another—or at least from the lower to the higher. Identicards were issued and checkpoints