I read an article today from the Smithsonian about Gobekli Tepe, a temple in Turkey that was recently dated to approximately 10,000 B.C. That would make it 6500 years older than the Great Pyramids and 6000 years older than Stonehenge. I am not aware of any similar sites as old as this one, but I would love to hear from someone who knows otherwise.
8,000 B.C. is generally accepted as the beginning of the Neolithic Age in the Middle East, but this is 2,000 years before that. This seems to imply that civilization was already old when Sumer and Egypt arose. At present, we know very little about this era. There is a minority position that a lost civilization preceded those ancient societies that we know. This is a minority position for good reason, because there are a lot of cranks and pseudo-scientists who say things like this. I don't know the field well enough to comment further, but there are tantalizing clues that there is much more yet to be found.
This is my favorite quote from the Smithsonian article, because it reminded me of something G. K. Chesterton said:
To Schmidt and others, these new findings suggest a novel theory of civilization. Scholars have long believed that only after people learned to farm and live in settled communities did they have the time, organization and resources to construct temples and support complicated social structures. But Schmidt argues it was the other way around: the extensive, coordinated effort to build the monoliths literally laid the groundwork for the development of complex societies.
In Orthodoxy, Chesterton said:
Morality did not begin by one man saying to another, "I will not hit you if you do not hit me"; there is no trace of such a transaction. There IS a trace of both men having said, "We must not hit each other in the holy place." They gained their morality by guarding their religion. They did not cultivate courage. They fought for the shrine, and found they had become courageous. They did not cultivate cleanliness. They purified themselves for the altar, and found that they were clean.
For those with an interest in lost history, I can recommend the Anthropogene, although the site seems sadly neglected now. There are many interesting articles to read in the site history, however.