Hyperion by Dan Simmons
From the publisher: On the world called Hyperion, beyond the law of the Hegemony of Man, there waits the 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 backward through time, the Shrike waits for them all.