Seven high school students interning at Green-Wood Cemetery surveyed land to rediscover lost graves. View Full Caption Ethan Boote

GREENWOOD HEIGHTS — High school students have unearthed and restored a dozen long-forgotten 19th century graves of free African Americans buried in Green-Wood Cemetery.

The graves date back to 1858 in what once was "The Colored Lots" for free African Americans. But because the plots were the cemetery's most affordable option at the time, they lacked a foundation to support the headstones, which gradually sank into the earth — disappearing with little trace.

Now seven summer interns from the High School for Architecture and Design in Williamsburg and the Mather Building Arts and Preservation High School in Hell's Kitchen have reclaimed the graves by plunging metal probes into the ground and digging for the grave markers.

"It was like solving a mystery," Antonio Rojas, an 11th grader at the High School for Architecture and Design told DNAinfo New York. "We knew something was there but we had to piece it together."

For six weeks the students pored over historic Green-Wood maps and Census records for a fuller picture. Records showed that 83 people were laid to rest there, but only 61 were accounted for, according to Green-Wood's manager of restoration and preservation, Neela Wickremesinghe.

Seven high school students interning at Green-Wood Cemetery rediscovered and restored the headstones of free 19th century African Americans. (Ethan Boote)

Students rediscovered a dozen sunken grave markers — at least 10 more are still lost — and worked to piece broken tablets together, cleanse the marble and granite of grime and reposition the restored tablets in their rightful place.

The junior preservationists also refurbished headstones that managed to stay above ground and planted white impatients at the plot's resurrected stones.

"This is important because the souls buried here were forgotten," said Khalilah Clark, a twelfth grader at the Mather School. "These people had historic significance and they deserve to be noticed."

The importance of the student's work is underscored by recent white nationalists' recent protests to preserve a statue of confederate Gen. Robert E. Lee in Charlottesville, Virginia, said Wickremesinghe.

"Their work is even more vital with the racism and bigotry we're seeing," Wickremesinghe said. "It's important that they understand that the world doesn't operate in a vacuum and we can find and highlight the connections to the past."

Students spent time physically restoring the graves, but also researched the individuals whose graves they worked on. (Ethan Boote)

Students combed Ancestry.com to learn more about those buried below including Andrew Schofield, a Civil War veteran who fought with the 125th New York infantry, and Daniel Hutchings, who worked as a waiter and knew how to read but not write, according to Clark.

It was an emotional undertaking for some of the students who knew their ancestors experienced the commonplace racism of the period.

"It's important because it's telling a story of how black people were treated back then," said Arnell Skinner, another twelfth grader at the Mather School. "It was a little emotional seeing some of these headstones broken into 80 pieces and knowing no one cared what happened, so I'm glad I had the chance to make sure they're remebered."