Take a close look at the stones of the Temple of Santiago Tlatelolco, and you’ll notice they reveal episodes from Mexico’s past. The 16th-century church was constructed with material from the destroyed pyramids of Tlatelolco. The pilfered stones were not randomly placed.

At the rear of the temple is a stone with the petroglyph of a deity. Many archaeologists agree that it is Tlaloc, the god of rain. Some propose that the stone was placed there by the indigenous people themselves, so when they were praying in the temple, they would actually be praying to Tlaloc behind the atrium. In front of the facade, there’s also a spiral-like design. The left side of the temple’s facade contains some stones carved with Spanish words. You can see names like “Ines” and “Juan.”

The building’s stones also bear scars of Mexico’s recent past. If you look carefully at the northern part of the temple’s facade, you’ll see marks from where bullets grazed the structure. These are remnants of the Tlatelolco massacre.

In 1968, students rebelled against the police repression of President Díaz Ordaz’s regime. Convinced that this was a coup d’état orchestrated by the communists, Ordaz, with the support of his cabinet, decided to end the protests, fearing that they would reach their peak during the Olympics, which the country was hosting that year.

On October 2, 1968, the students gathered for a peaceful protest in the Plaza de las Tres Culturas, which is near the temple. Members of the Olympia Battalion, an elite secret security force assembled for the upcoming Olympics, were planted in buildings around the plaza. The Olympia Battalion fired shots at the army—a scheme that had been hatched to make it look like the students had instigated the attack—and the army quickly returned fire.

Students and innocent bystanders were slain. Though witnesses gave their testimonies, it wasn’t until the secret documents were unsealed that the truth about the government’s role in the massacre was fully revealed.