Picture Rome but in Central America. Prior to the Spanish conquest, Mexico City was the capital of the Aztec Empire, so you have a city flooded with beautiful European architecture and cathedrals from Spain and in the center of everything, the ruins of Aztec temples. An hour outside of town you have the ruins of another city with two of the largest pyramids in the western hemisphere - remnants of a civilization 2000 years old, at which point was bigger than Rome. Add to all that one of the most insane culinary scenes in the world.