Across a Billion Years

Across a Billion Years is a 1969 science fiction novel by American writer Robert Silverberg.

Plot
Set in the year 2375, it follows Tom Rice, a young archaeologist attached to a two-year dig on the planet of Higby V. He is searching for artifacts belonging to a long-lost and ancient race known simply as The High Ones. Throughout known space, details of this billion-year-old civilization have been uncovered on many planets. What seems like a fairly straightforward expedition becomes a galactic odyssey when an artifact never seen before is discovered. This device hints that perhaps the High Ones are not extinct at all.