As noted above the model for Camp 6 is the US prison at Terre Haute, Indiana, designed by Schenkel Schutz:

U.S. Army Col. Bruce Vargo, center, the joint detention group commander, gives Chairman of the Joint Chiefs of Staff Navy Adm. Mike Mullen a tour of a detainee recreation area at Camp Six on Naval Station Guantanamo Bay, Cuba, Jan. 13, 2008. Mullen, who is on a five-day trip to the U.S. Southern Command area of operations, is visiting detention facilities and the new expeditionary legal complex where high value combatants will be tried. DoD photo by Mass Communication Specialist 1st Class Chad J. McNeel ey, U.S. Navy. (Released) Download Hi-Res

What appears to be a low structure at left of Camp 6 does not show in photo below.