Zacarias Moussaoui looks set to live out the rest of his days in a super-maximum security Colorado prison, dubbed "the Alcatraz of the Rockies".
Supermaxes are the highest security lock-ups in the US
Officially it is the "Administrative Maximum" facility at the Florence Correctional Complex (FCC). It is the federal Bureau of Prison's highest security lock-up and is already home to a number of other prisoners incarcerated as part of what the US calls its war on terror.
British "shoe bomber" Richard Reid is held there. Omar Abdel-Rahman, jailed for conspiracy after the 1993 bombing of the World Trade Center, is also believed to be an inmate.
Ramzi Yousef, also implicated in the 1993 plot, is also behind bars at the institution known for its harsh conditions.
ADX Florence is one of three main prisons at the FCC site, located in mountainous, rural isolation some 90 miles south of Denver.
Built in 1994 at a cost of about $60m, ADX Florence is said to be equipped with 1,400 remote-controlled steel doors, motion detectors, pressure pads and gun towers with perfect sightlines across the complex.
Tightly controlled and technologically advanced, such facilities are designed for the most dangerous and disruptive prisoners - and have been a source of controversy for many years.
Solitary confinement is an almost permanent way of life, with ADX Florence's 400-or-so prisoners locked in spartan cells for at least 23 hours each day.
An hour each day can be spent in a concrete-walled recreation yard.
A typical "Supermax" cell's furniture - bed, desk, stool - is made from poured concrete.
The cells are equipped with showers that run on a timer, and a toilet that shuts off if plugged. Meals are delivered to inmates in their cells to restrict interaction.
Each cell also is equipped for 24-hour video and audio surveillance.
Inmates are allowed up to five non-contact visits per month, each lasting no more than seven hours.
Yet it is thought Moussaoui will be held under special conditions that will prevent him from having any contact with the outside world.
Supermaxes tend to be the end of the road for those in the prison system.
Transfer to an even marginally less restrictive environment can require several years of good behaviour.
To their supporters, these jails are the most appropriate way to house the worst of the worst in the prison population.
Critics describe them as a breeding ground for monsters - with regimes that are tantamount to torture.
TYPICAL FACILITIES IN A SUPERMAX PRISON CELL
1. Typical cell sized 7ft x 12ft (3.5x2m) with small slit window
2. Shower works on timer
3. Small black and white TV showing educational programmes (some prisoners only)
4. Heavy duty steel door or grate
5. Writing desk
6. Toilet which shuts off if blocked
8. Steel mirror, rather than smashable glass