Looking for history rabbit holes to fall into.
For me it has always been the Bronze Age Collapse - how exactly did almost every major civilization near Greece and Egypt that was thriving in 1200 BCE just collapse or drastically weaken over a span of ~50 years? Related mystery - where did the Sea Peoples, raiders who are proposed to have played a role in the collapse, even come from?
What happened to the Kruger Millions? My cousin used to live near the Blyde River Canyon, and he would always have a story about a new group of treasure hunters who were sure they had figured it out. Obviously, no one ever did. And then a couple years ago, some coins from the era turned up in a Swiss bank vault. So did someone find the treasure? Was it ever actually buried in South Africa at all? WHO KNOWS!