66,000 pieces of art, donated by one of the world's richest men.

The only castle in North America to ever house European sovereigns.

An Aztec temple, the largest man-made pyramid in the world, sits buried in earth with a Spanish church set on top.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

Gilded heaven for philatelists and architecture freaks, still in full working order despite sitting atop tremulous ground.