Hyperion by Dan Simmons

On the world called Hyperion, beyond the reach of glactic law, waits a creature called the Shrike. There are those who worship it. There are those who fear it. And there are those who have vowed to destroy it. In the valley of the time tombs, where huge, brooding structures move backwards through time, the Shrike waits for them all. 

On the eve of armegeddon, with the entire galaxy at war, seven pilgrims set forthon a final voyage to Hyperion seeking awnsers to the unsolved riddles of their lives. Each carries a desperate hope - and a terrible secret. And one may hold the fate of humanity in their hands.