For nearly three years, there have been reports and rumors of millions of dollars being spent at Guantánamo Bay Naval Station (aka "Gitmo") to receive new U.S. prisoners -- tried in military courts under the UCMJ.
During that time, the current Detention Area (at lower right [east], above) has been under regular "OHI" (OverHead Imagery) surveilllance. Despite debunked false propaganda, the last visible Detention Area change was in 2011 -- when an exercise yard was added.
But, recently, surveillance has detected construction activity at the far left [west] end of the military property --just northwest of the currently-active airfield.
Now, the new detention area looks like this:
The site appear to be laid out to accommodate several hundred more such structures.
BUT -- One 20' X 36' slab floor will support a tent or pre-fab structure that can accommodate two prisoners luxuriously or four prisoners in jail-sized quarters.
That means the 144 slabs already poured can accommodate 288 or 576 prisoners readily.