Feathered and fire serpents adorn the steps of the Quetzalcóatl Pyramid. Some weathering has occurred in the past 17 centuries, but once the eye sockets held black obsidian volcanic glass, the flames were painted bright red and feathers adorned with green jade. The museum (show your gate ticket for admission) near the Sun Pyramid shows murals, artifacts and has a large model of the site, which helps add details to the huge structures outside. None of the three pyramids can be climbed now, but I still walked a couple miles round trip, including the Moon Pyramid near where I started. I arrived early at 9 am, just as the hot air balloons were descending after their dawn tours. It’s an awesome place, but it can get hot and crowded by midday. I recommend staying nearby the night before.

At its peak, Teotihuacán was the largest city in the Americas, 6th largest in the world. Roughly, the city began sometime around 200 BC and fell around 550 CE. Much of their wealth came from obsidian tools, weapons and art, mined from local volcanoes and expertly knapped. The pyramids and related buildings show an elaborate religious class, but few signs of military or monarchs. The pyramids are designed to make observations for the Mesoamerican calendar, so the priests likely derived their power by determining the seasons. Best guess is that their civilization’s collapse was internal, with signs of drought and starvation, before simultaneous fires burned out the elites. The priests essentially had one job—to monitor the climate—, and they failed. Human success, growth, unsustainable use of natural resources, crop failure, and collapse, is a common pattern in ancient civilizations, and we are likely on a similar path due to carbon pollution.