"Humanity would have to rethink its understanding of the cosmos, alongside the stern warning not to unearth those mysterious remnants of unknown masonry."
Synopsis: A professor wakes up from a long, vivid nightmare to discover that five years have passed since the mental collapse that caused him to lose consciousness; during that time, his body continued to move and act strangely, having been inhabited by the mind of an ancient entity with a thirst for knowledge.
They were watching us long before humanity existed, and they still are.