This will probably be the final Indy film for the spry septuagenarian (climbing in and out of excavation trenches does a number on the knees, to say nothing of fighting off Nazis and Russian spies).

So what should Indy find for his last archaeological hurrah? Last year National Geographic archaeology fellow Fredrik Hiebert shared seven ancient mysteries he thinks we'll solve this century, from discovering lost civilizations in South America and the tombs of legendary leaders like Genghis Khan and Alexander the Great, to deciphering the language of the Minoans and recovering an intact Neanderthal. (See the seven ancient mysteries archaeologists will solve this century.)

We asked Hiebert, who has also curated the National Geographic Museum