I know this is a joke/meme, but I sincerely think of the Roman Empire a surprising amount of times. I find myself obsessing over how Roman citizens were living just as complex lives as we are today, or about Marcus Aurelius’ life and philosophy, or about how the Republic fell and became a totalitarian state.
Probably a few times a week average, and I’m not much into history but into the aesthetics and cultural legacy. After all… Most RPGs reference it somehow, so it’s not that hard to find triggers for thought.