Teotihuacán and Tula
Concierge.com's insider take:
There's no need to head to the jungle to see the region's archaeological sites; two of the best are just north of the capital. (Buses leave regularly from the Terminal Central del Norte, just north of downtown, 4907 Eje Central Lázaro Cárdenas; 52-55-5133-2444; www.centraldelnorte.com). Teotihuacán, once home to 250,000 people, predates many other Aztec, Toltec, and Maya cities by centuries. Most people huff and puff their way up the massive Pyramid of the Sun, but there's an easier climb (and a far better view) at the slightly smaller Pyramid of the Moon. Make sure to see the wonderfully preserved frescoes in the more recently excavated private homes near the temples. (Ask an attendant to point out a depiction of a dentist working on a patient.) At nearby Tula, a city that rose to power after the fall of Teotihuacán, a platoon of stone soldiers stands guard atop a temple.