A sinkhole - once a local curiosity in Iraq - has reportedly been turned into a mass grave for up to 4,000 victims of Islamic State killers.
Local residents living near the Khasfah - the Arabic word for a sinkhole - have described how ISIS transformed the area into a "place of death" after capturing it in 2014.
Villagers say the sinkhole, outside Mosul, was used as an execution site and a mass grave where bodies were dumped.
Mohamed Yassin, 56, who lives in nearby Hammam al Alil, said: "They would bring them blindfolded, their hands tied behind their backs.
"The Khasfah would be in front of them, they would make them kneel down, shoot them in the head and push them in.
"People became afraid of the place, it became a place of death, a place where you'd be executed."
Yassin said he saw executions take place there on at least six occasions, and most of those killed were police officers, soldiers or government workers.
Hussein Khalaf Hilal, 73, said he was taken to the site by ISIS fighters who accused him of breaking their religious rules.
"They came to the house, they blindfolded me, tied my hands behind my back and took me away in a car with blacked out windows," he said.
"They took me there because they wanted me to pledge allegiance, to frighten me."
He said ISIS fighters marched people into the pit after forcing them to take pills.
"They would line them up, 10 by 10, 15 by 15," he said.
He was eventually spared and taken to prison instead.