Mexico City

Mexico City is the oldest capital in the Americas, built on top of the Aztec one, and it feels like it. Around the Zócalo you can stand on Aztec temple foundations, walk into a sixteenth-century cathedral and then eat at a restaurant that just made the world's top fifty list. Roma and Condesa are the leafy neighborhoods with the cafés and galleries; Coyoacán is Frida's village; Polanco is the money.

The food is the reason most people come back. Street-level, it is the best in the world. Give it four days minimum, walk everywhere, use the Metro and the taxis apps, and go to the Anthropology Museum on the first morning.