The city is winched along tracks through a devastated land full of hostile tribes. Rails must be freshly laid ahead of the city & carefully removed in its wake. Rivers & mountains present nearly insurmountable challenges...The city is winched along tracks through a devastated land full of hostile tribes. Rails must be freshly laid ahead of the city & carefully removed in its wake. Rivers & mountains present nearly insurmountable challenges to the ingenuity of the city's engineers.