Lost cities / archaeology / ancient history

It is fascinating, and very well-publicised work. Anyone who likes this will find lots more. I haven't tried too many Internet rabbit holes, but I've long found this to be one of the most enjoyable. You just have to avoid the Erich von Däniken-style esoteric bullshit (and there's considerably more of that than all the archaeological evidence ever gathered). :)

There is so much still hidden in the ground to wean us off our modern prejudice that 'civilisation' only really began at the end of 'pre-history'. Memories are so short, and a stone-built ritual centre like that at Göbekli Tepe would have been surrounded by large population centres built up with less durable materials, as at Stonehenge. I don't really believe the theories that such sites were only used seasonally. They undoubtedly attracted more visitors at certain times, but I think they must have been large cities in their own right. As with all ancient cities, it's harder to find evidence of more perishable materials than stone, e.g. Babylon was undoubtedly much, much bigger than just the area enclosed in its walls, and outside them it would have been what we'd call a shanty town today.

All that said, of course these spectacular sites inevitably attract a huge amount of speculation, and interpreting them is difficult without enough evidence, so the above speculation may well be completely wrong, but it has recently been shown in the Maya domains and at Angkor that they clearly had much larger populations than previously suspected. As with Stonehenge, people tend to focus on things like religion and ritual, artefacts, or other evidence of culture and artistry, but around them a lot of completely mundane life went on that's at least equally as interesting when it comes to writing histories.