Think Alcatraz, but a lot colder…
The NYT has a super in-depth and interesting piece on life inside the ADX in Colorado, where they keep the worst of the worst ranging from Ted Kaczynski and the Atlanta Olympics bomber Eric Rudolph to 9/11 conspirator Zacarias Moussaoui and 1993 World Trade Center bombing mastermind Ramzi Yousef.

The United States Penitentiary Administrative Maximum Facility, otherwise known as the ADX, in Florence, Colo. Where they would keep Magneto if he existed…
The ADX can house up to 500 prisoners in its eight units. 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.”
And yes, sometimes I think to myself, as long as I had an internet connection that I could pull it off…