Archaeological zones are hotspots for those who practice traditional observances of the vernal equinox the halfway point between winter and summer.
Clear skies welcomed the arrival of the spring equinox on Sunday at the towering Pyramid of the Sun northeast of Mexico City, where the occasion has come to be celebrated with ritual dances, drumming and incense.
The vernal equinox the halfway point between winter and summer was arriving late Sunday afternoon at the pyramids of Teotihuacan, the sprawling Pre-Hispanic religious site 30 miles (50 kilometers) from the capital.
Workers at archaeological zones across Mexico braced for an onslaught of visitors on Monday, the first full day of spring.
It also is a popular day to visit Chichen Itza, the most famous of Mayan ruins on the Yucatan peninsula, and watch the a serpent-shaped shadow slither down the Temple of Kukulkan at daybreak.
Even relatively unknown archaeological sites are hot spots on the equinox, as Mexicans revisit ancient times. Managers expected about 15,000 visitors on Monday at the rounded pyramid at Cuicuilco, in southern Mexico City.
Each year pilgrims of diverse beliefs stream to the sun temple and adjacent Pyramid of the Moon at Teotihuacan, set in cactus-studded highlands.
Sunday marked 100 years since archaeologists began formal explorations of the site, clearing away a thick vegetation that had blanketed the pyramids.
Teotihuacan emerged about two centuries before the birth of Christ and included as many as 200,000 people at its peak. But the city began declining sharply around 650 A.D., and was almost completely abandoned around 750 A.D., for unknown reasons.