What it's like inside America's toughest prison

More than 40 US states run "super-maximum security" prisons for particularly violent or ill-behaved convicts. But the federal government runs only one "Supermax:" the notorious US Penitentiary Administrative Maximum Facility in Florence, Colorado.

More widely known as the ADX or the "Alcatraz of the Rockies," it's the highest-security prison in the entire country. There, every inmate spends roughly 23 hours a day in solitary confinement, The New York Times reported in a lengthy article over the weekend.

The ADX was designed for "a very small subset of the inmate population who show absolutely no concern for human life," Norman Carlson, the former director of the Federal Bureau of Prisons, has said, according to The Times. The ADX currently houses 422 inmates, including some of the world's most infamous names, like the Unabomber.

The Times described their daily life like this:

Inmates spend their days in 12-by-7-foot cells with thick concrete walls and double sets of sliding metal doors (with solid exteriors, so prisoners can't see one another). A single window, about three feet high but only four inches wide, offers a notched glimpse of sky and little else. Each cell has a sink-toilet combo and an automated shower, and prisoners sleep on concrete slabs topped with thin mattresses. Most cells also have televisions (with built-in radios), and inmates have access to books and periodicals, as well as certain arts-and-craft materials. Prisoners in the general population are allotted a maximum of 10 hours of exercise a week outside their cells, alternating between solo trips to an indoor "gym" (a windowless cell with a single chin-up bar) and group visits to the outdoor rec yard (where each prisoner nonetheless remains confined to an individual cage). All meals come through slots in the interior door, as does any face-to-face human interaction (with a guard or psychiatrist, chaplain or imam). The Amnesty report said that ADX prisoners "routinely go days with only a few words spoken to them."

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In 2012, Michael Bacote, an illiterate inmate with an IQ of 61, along with a handful of other inmates, sued the government, alleging the ADX violated their basic rights by placing them in such deplorable conditions. It's the largest lawsuit ever filed against the Federal Bureau of Prisons.