Cuicuilco

Before Teotihuacan, the valley's great city was Cuicuilco - and its centerpiece survives as one of the oldest monumental structures in the Americas: a circular stepped pyramid some 110 metres across, raised around 800-600 BC when circular temples were still the fashion. Around 250 AD the Xitle volcano on the Ajusco slopes erupted and drowned the city in lava, entombing everything but the great platform's upper body and scattering its people - many, archaeologists believe, toward a rising Teotihuacan. The Pedregal lava that destroyed Cuicuilco also preserved it: visitors climb the ramped circular tiers above a sea of black stone now grown with cactus and pepper trees, an ecological island amid the traffic of Insurgentes Sur. A small site museum holds figurines and explains the eruption's archaeology. It is a modest, strangely moving site - the city's oldest architecture standing in its newest sprawl, with the volcano that killed it visible on the southern skyline.

What you actually see

• The circular pyramid - ramped tiers of one of the hemisphere's oldest monuments.
• The lava field - the Xitle flow that buried the city, now a cactus reserve.
• The site museum - figurines and the eruption story.
• The skyline contrast - ancient platform against Insurgentes towers.

When to go

Dry-season mornings for clear light on the lava; the exposed site bakes at midday and greens attractively in the summer rains.

Honest expectations

This is an archaeological quiet spot, not a Teotihuacan - one main structure and a walk, done in ninety minutes. Signage is modest. The surrounding avenues roar; the site itself absorbs the noise surprisingly well.

Nearby

The UNAM Ciudad Universitaria murals and Olympic stadium lie just north; San Angel is fifteen minutes up Insurgentes.