The day of the empty lot, of the city block unencumbered by parked cars, of the stoop, is over. In the cities there is virtually no empty space and what there is of it is given over to asphalt-paved parking lots and to public parks with carefully delineated fields and playing areas. The automobiles, the delivery trucks, the buses and the taxis pack the streets. What had been empty space is now divided into lots each with its tract house and its lawn. Unbuilt-upon land has been turned into ball fields where organized teams play, into golf courses and tennis courts and fenced-in paddle ball and handball courts. Stoops have been reduced to one