Sawyer's report from inside the notorious prison, airs on Friday.
Diane Sawyer has gone to "Hell," at least as far as prisons go.
Read: Inmates Caught Breaking Back Into Prison One Day After Making Their Escape
The journalist got unprecedented access to solitary confinement at New York’s notorious Rikers Island prison.
In a promotional clip, an inmate shouted: "They treat us like animals in here!"
In the prison, 165 inmates are locked up there for 23 hours a day. Sawyer was told “this is the punishment for inmates who attack officers or each other.”
The story inside America’s largest prison complex was two years in the making. Sawyer spent seven days on the island as it faces public pressure to be shut down.
Read: 7 Cases of Men Who Spent Years Behind Bars For Crimes They Didn't Commit
In the report, she interviews Joseph Ponte, Commissioner of the New York City Correction Department, about his vision to reform the prison.
This special edition of Sawyer’s exclusive report, "Hidden America: Inside Rikers Island," airs Friday night on Nightline.
Watch: 'Barefoot Bandit' Wants to Freeze His Dying Mom: 'She Won't Be Alive When I Get Out'
