The City of Ice - K. M. McKinley

Deep in the polar south stands a city like no other, a city built aeons ago by a civilisation mighty and wise. Locked in a race with a rival engineer, Trassan Kressind's great iron ship crosses uncharted seas. The City of Ice promises the secrets of the ancients to whomever can reach it first. It may prove too little knowledge too late, for the closest approach of the Twin in 4000 years draws near, an event that has heralded terrible destruction in past ages. As the Kressind siblings pursue their fortunes, the world stands upon the dawn of a new era, but may yet be consumed by a darkness from the past. Industry and magic, gods and steampower collide in the epic sequel to The Iron Ship.