I think the story you’re referencing was a burial ground. Not necessarily evidence of child sacrifice like it was spun in the media.
You might be referring to this story:
Mass grave of babies and children found at Tuam care home in Ireland
I was actually posting about news stories from the 80s in Mexico. Pretty close to what happened in the above, but in Mexico City specifically. When they demo’ed churches in the aftermath of the 1985 Earthquake they found bodies as well - probably going back decades. I doubt it was done out of child sacrifice, but rather to cover up their abuse.