In a town in western Ireland, where castle ruins pepper green landscapes, there’s a six-foot stone wall that once surrounded a place called the Home. Between 1925 and 1961, thousands of “fallen women” and their “illegitimate” children passed through the Home, run by the Bon Secours nuns in Tuam.

Many of the women, after paying a penance of indentured servitude for their out-of-wedlock pregnancy, left the Home for work and lives in other parts of Ireland and beyond. Some of their children were not so fortunate.

More than five decades after the Home was closed and destroyed — where a housing development and children’s playground now stands — what happened to nearly 800 of those abandoned children has now emerged: Their bodies were piled into a massive septic tank sitting in the back of the structure and forgotten, with neither gravestones nor coffins.

“The bones are still there,” local historian Catherine Corless, who uncovered the origins of the mass grave in a batch of never-before-released documents, told The Washington Post in a phone interview. “The children who died in the Home, this was them.”

More: Bodies of 800 Babies, Long-Dead, Found in Septic Tank at Former Irish Home for Unwed Mothers