At its peak around AD300, more than 1,000 years before the Aztecs arrived in the vicinity, the city of Teotihuacan covered eight square miles and housed some 150,000 people. Three hundred years later the civilisation disappeared, although nobody really knows why. The highlight of the ruins are two great pyramids and an avenue lined with temples.
Teotihuacan is 30 miles north of the city - you can get a bus from the northern terminal every 15 minutes, or arrange a price with a taxi; Mon-Sun 8am-5pm; admission 35 pesos
Updates
If you can arrange your trip to coincide with the spring equinox you will see thousands of people dressed in white to absorb the special energy said to emenate from the pyramids on this day. There's an interesting partially subterranean restaurant nearby to the pyramids (easily walkable) - I can't remember it's name, sorry (can anyone help?)...Diners sit in a huge cavern, on different levels. The food's ordinary but the atmosphere unique
One seriously annoying thing to watch out for: the souvenir retailers. They're all over the place, and the quality of the numerous (fake) artefacts and so-called genuine 2,000-year-old pieces of stone should be doubted to say the least: our beautiful allegedly ancient Aztec sculpture sold to us by one particularly enthusiastic man (“It's almost as hard as diamond!”) broke its nose a week after our return flight. Beware.
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