This is right out of any RPG...well one as cool as Castles & Crusades anyway (shameless random plug). A pyramid in Mexico has been the object of a great deal of attention after an archeologist found liquid mercury at the bottom of a shaft. He is speculating that it hides a corridor that may lead to a burial chamber.
Now, regardless of what the outcome of this find is, its a great concept and one that should find its way into some adventure somewhere in something.
But check the article out. Its all kinds of cool stuff they are finding down in Mexico and in these pyrmaids. If you didn't love the Mayan/Incas/Aztecs already, you'll love em now. Read on.
Ps: The Mayans were in the Yucatan Pennisula, the Incas in North Central South Amerca and the Aztecs in Mexico.