The Pyramid of the Sun is the largest pyramid in the Americas — roughly 220 metres on each side at the base and rising over sixty metres above the plain. It dominates the eastern side of the Avenue of the Dead, oriented to mark the setting sun on two days of the year that frame the planting season. The pyramid was built in two main phases between roughly 100 and 200 AD; the outer shell of stone and stucco that you see today is largely a reconstruction by Leopoldo Batres after 1905, though the core is original.
Climbing the pyramid is the great Teotihuacan ritual — 248 steep steps to the summit and a view over the whole valley — but access has been intermittent in recent years following stabilisation work and most recently a security incident in early 2026. When open it is normally first-come, first-served from 9 am. Even with the climb closed, walking around the base gives a sense of the staggering scale of pre-Hispanic engineering: the pyramid contains roughly three million cubic metres of material, all of it dragged into place by hand.