I remember seeing a video demonstration of how a single person can erect stones as in Stonehenge. Basically, you lever it up bit by bit by placing a log or b other fulcrum under the stone, off-center, and place weights on the shorter end until the other end of the stone lifts. Add a higher fulcrum on the other side, repeat until the stone is high enough to be tipped into a hole dug into the ground to hold it.
It's impressive, yes. And probably we don't know exactly how it was done. But that's not the same as saying it's an unexplained mystery - we just don't know which particular methods they used, even if we know one or more ways in which it could have been done.
An explained mystery would be something for which the method would be non-obvious, but nonetheless the method was known. Like a magic trick the solution of which were pubic knowledge - mysterious but explained in sources in the public domain.
So what's something where we can come up with several plausible methods, but don't have the evidence to conclusively decide which method actually was used?
