All Kathryn Peirce knew about her mother's twin was that the baby died at birth and was probably a boy. After years of research, her cousin uncovered a birth certificate that revealed the baby was actually a girl. They also learned she was buried at St. Joseph cemetery in Boston in 1923, though Peirce couldn't find a cemetery of that name in the city.

The mystery was solved this year when archeologists discovered a forgotten burial site on the grounds of St. Joseph church in Boston's Roxbury section.

On Saturday, Peirce's aunt was honored along with more than 1,200 others in a ceremony led by officials from the Boston Archdiocese.

Bishop Walter J. Edyvean and The Rev. Walter Waldron, former pastor at St. Joseph, led more than 60 people who gathered at Calvary Cemetery in Waltham to dedicate the new, final resting place for the bodies forgotten for decades.

"We don't think the baby had a ceremony or a blessing, so this was nice," Peirce said.

St. Joseph church was built in 1845 and the cemetery established soon after. By 1868 it had filled, mostly with young families of Irish immigrants who presumably fled their home country during the potato famine.

By 1882, according to the archdiocese, the cemetery had been wiped from city maps and tombstones had disappeared.

Earlier this year, the church property was sold to the Roxbury Charter High School. During preliminary surveys, an archaeological team found a human bone. The team, as well as members of the church, had mistakenly believed that the bodies from the cemetery were exhumed and reinterred elsewhere, said Kirk VanDyke, one of the field archeologists.

When the work was finished, the team had recovered the remains of 1,238 people.

"I don't think that anyone expected so many people," VanDyke said. "Every scoop full of dirt, we hoped it would be that last."

There was no map of the grave site, according to Robert Visconti, executive director of The Catholic Cemetery Association of the Archdiocese of Boston, so the bodies were exhumed one grave shaft at a time. They were recently reinterred at the Calvary Cemetery.

A statue of St. Joseph stands in a flower bed at the center of the new plot atop a podium that was found at the excavation site among the rubble of broken headstones.

Attached is a plaque with an Irish phrase that would have been common on a mid-19th century tombstone, which translates to "To the right of God their souls will sit."

After learning about the burial site at St. Joseph, Peirce and her family decided to give her aunt a "good, Irish name": Francis Therese Wrenn.

Peirce said her mother, who was buried at a Calvary Cemetery in nearby Woburn, would be happy her sister received a proper burial.

"It's just ironic, they're both at Calvary," Peirce said. "It's like the twins are in the same cemetery."