Strength of Stones by Greg Bear

held him comfortably but securely. He didn't try to straggle. The room was disassembling itself. Panels beneath the racks retracted, and wheels jutted out. Shivering with their new energy, the racks elevated and wheeled out their charges.
    The racks formed a long train down a hall crowded with scurrying machines. Behind them, the hall took itself apart with spewed ropes, fresh-spouted grasping limbs and feet, wheels and treads.
    It was a dance. With the precision of a bed of flowers closing for the night, the city shrank, drew in, pulled itself down from the top, and packed itself onto wide-tread beasts with unfathomable jade eyes. The racks were put on the backs of a trailer like a flat-backed spider, long multiple legs pumping up and down smoothly. A hundred spiders like it carried the remaining racks, and thousands of other choreographed tractors, robots, organic cranes, cyborg monsters, waited in concentric circles around Mandala. A storm gathered to the south about Arat's snowy peaks. As the day went on and the city diminished, the grey front swept near, then over. A mantle of cloud hid the disassembly of the upper levels. Rain fell on the ranks of machines and half-machines, and the ground became dark with mud and trampled vegetation. Transparent skins came up over the backs of the spider-trailers, hanging from rigid foam poles. Thinner crawled between the racks and approached Jeshua, who was stiff and sore by now.
    "We've let the girl loose," Thinner said. "She has no place to go but with us. Will you try to leave?"
    Jeshua nodded.
    "It'll only mean trouble for you. But I don't think you'll get hurt." Thinner tapped the rack, and the clamps backed away. Night was coming down over the storm. Through the trailer skin, Jeshua could see the city's parts and vehicles switch on interior lights. Rain streaks distorted the lights into ragged splashes and bars. He stretched his arms and legs and winced.
    A tall tractor unit surmounted by a blunt-nosed cone rumbled up to the trailer and hooked itself on. The trailer lurched and began to move. The ride on the pumping man-thick legs was surprisingly smooth. Mandala marched through the rain and dark.
    By morning, the new site had been chosen.
    Jeshua lifted the trailer skin and jumped into the mud. He had slept little during the trek, thinking about what had happened and what he had been told. He was no longer meek and ashamed.
    The cities were no longer lost paradises to him. They now had an air of priggishness. They were themselves flawed. He spat into the mud.
    But the city had made him whole again. Who had been more responsible: the architect or Mandala itself? He didn't know and hardly cared. He had been taken care of as any unit in Mandala would have been, automatically and efficiently. He coveted his new wholeness, but it didn't make him grateful. It should have been his by a birthright of ten centuries. It had been denied by incompetence -- and whatever passed as willful blindness in the cities.
    He could not accept it as perpetual error. His people tended to think in terms of will and responsibility.
    The maze of vehicles and city parts was quiet now, as if resting before the next effort of reassembly. The air was misty and grey with a heaviness that lowered his spirits.
    "'Ere dis you go?"
    He turned back to the trailer and saw the girl peering under the skin. "I'm going to try to get away," he said. "I don't belong here. Nobody does."
    "Lissy. I tol' de one, T-_Thi_nner to teach dis me ... teach me how to spek li' dis you. When you come back, I know by den."
    "I don't plan on coming back." He looked at her closely. She was wearing the same shift she wore when he first saw her, but a belt had tightened it around her waist. He took a deep breath and backed away a step, his sandals sinking in the mud.
    "I don' know 'oo you are ... who you are ... but if Th-Thinner brought you, you must be a good person."
    Jeshua widened his eyes. "Why?"
    She shrugged. "Dis me just know." She