Across a Billion Years
by Robert Silverberg
Media: Mass market paperback
Cover art: Dell Harris
Scattered throughout the globe of human-occupied space is evidence of a civilization that bestrode the galaxy before humanity was born. Now, a strange device has been discovered that shows the details of that great civilization. The details include a star map and hints that the High Ones are not extinct after all.
The map beckons, and humans, being what they are, will follow. To the next great step in human destiny—or ultimate disaster.