In a lot of cases, it's pretty hard to tell what's even going on in a photo until somebody explains it. And the older that photo is, the farther we're removed from its context, which makes it even harder to explain.
Fortunately, piecing together the puzzles of the past is the stock and trade of historians and they've already done a lot of work to fill in the blanks on some mysterious moments in history.
So today, we're going to have a look at some pics that don't really click without the right explanation.