Well, I was pretty sure this movie would be ludicrous, and it was. Does that mean it's not fair of me to complain about some of the, um, ludicrosity? Because it really is just completely unconvincing and doesn't bear a second of scrutiny.
So here's the backstory. This is all the stuff that happened before the movie starts. First, there's Cibola, the fabled City of Gold. That turns out to be in South Dakota, even though the movie says it's either Aztec, Mayan, or Olmec. At some point, Queen Victoria -- no, wait. That's not right. I think what happened is that someone (we don't know who) buried it under a mountain and built incredibly elaborate counterweights and things. As you do. Then the guy who made the Statue of Liberty knew about it somehow and hid a couple of Aztec (or Mayan or Olmec) planks in a couple of desks, then put a reference to that on one of his statues. Then Queen Victoria, who knew about it from some other means, sent a coded message to the Confederate army, who didn't do anything about it until after the war was over. Then John Wilkes Booth and some buddies went to a cryptographer (who hung out in a bar all day hoping someone would bring him a puzzle), who started to decode it and then burned the pages from Booth's diary.
And then we jump to the present day and Nicolas Cage, Jon Voight, Helen Mirren, and a couple of other people work through the riddles. My question is: when you have a fabulous treasure, what's the point of doing all this? First you hide it so no one will ever find it, and then you write an elaborate riddle telling people where it is? And then you write another riddle pointing people to that riddle? And then repeat a few times? If you want to hide it, stop putting coded directions everywhere; what are you, the Riddler? Conversely, if you want people to know where it is, just tell them! Just say "It's under that giant mountain over there!"