Mexico City

Mexico City needs 4 days: the Zócalo and historic center on one, Chapultepec and Polanco on another, Coyoacán and Frida Kahlo on the third, and Teotihuacán as an excursion on the fourth. March-May avoids summer rains and the dry cold of winter at 2,240m altitude. It's among Latin America's cheapest capitals for foreign tourists. It's the most populous city in North America, built literally over the ruins of Tenochtitlán, the Aztec capital, making it a place where pre-Hispanic pyramids, colonial architecture and modern skyscrapers coexist within just a few blocks.