MEXICO CITY, Mexico (AP) -- Archeologists said Wednesday they have discovered a massive 6th-century Indian pyramid beneath the site of a centuries-old re-enactment of the crucifixion of Christ.

Built on a hillside by the mysterious Teotihuacan culture, the pyramid was abandoned almost 1,000 years before Catholics began re-enacting the crucifixion there in the 1800s, unaware they were celebrating one of the holiest moments of their faith on a site originally dedicated to gods of earth, wind and rain.

While residents around the hillside in Iztapalapa, on the east side of Mexico City, express pride at the discovery, it illustrates the difficulty of preserving the many layers of Mexican history: archaeologists have decided not to fully excavate the site so as to avoid disturbing the Christian rites.

"When they first saw us digging there, the local people just couldn't believe there was a pyramid there," said archaeologist Jesus Sanchez. "It was only when the slopes and shapes of the pyramid, the floors with altars were found, that the finally believed us."

"The majority of the people now feel happy and proud, and have helped out a lot" in protecting the relics, Sanchez said.

The people of Iztapalapa -- now a low-income neighborhood plagued by squatter settlements -- began re-enacting the Passion of Christ in 1833, to give thanks for divine protection during a cholera epidemic.

During the ritual, which draws as many as a million spectators every year, a wooden cross is raised just a few yards from the buried remains of the Teotihuacan temple, and a man chosen to portray Christ is tied to the cross.

Archeologists said they will fill in the excavation pits that revealed the pyramid to prevent the structure from being damaged by Good Friday spectators.

"Both the pre-Hispanic structure and the Holy Week rituals are part of our cultural legacy, so we have to look for a way to protect both cultural values," said Sanchez, who, along with archaeologist Miriam Advincula, has been exploring the site since 2004.