A guard tower looms over a federal prison complex which houses a Supermax facility outside Florence, in southern Colorado, Thursday, Oct. 15, 2015. The prison is among those being assessed by a team of Pentagon officials as potential sites to house Guantanamo detainees amid the Obama administration's stalled effort to close the controversial facility.
Prisoners work at Belbaltlag, a Gulag camp for building the White Sea-Baltic Sea Canal . From 1932 documentary film, Baltic to White Sea Water Way. Courtesy of Central Russian State Film and Photo Archive.