THE UNDERSURFACE OF CRADLE, ONLY VISIBLE TO PEOPLE STANDING on the ground—more specifically, on the equator—looking up at it, was flat and generally egg-shaped, elongated in the direction of its east-west movement. On closer inspection its mostly smooth surface was interrupted from place to place by small hatches, carefully engineered protrusions, orifices, and other details. These were distributed around that otherwise featureless surface in a way that suggested orderly minds at work, addressing complications posed by the asymmetries of the city above.