Dracula, in specific, is written about one these folks.
And what they are most afraid of is large crowd with pitchforks and torches.

One way to "extend" life, to avoid the reaper, the karma (they think) is to have sex with a woman, and at the moment of inception, force your consciousness into the new baby.

These creatures are not the builders or designers of that ancient architecture, they are the same parasites that leached off of them.