GUANTANAMO BAY NAVY BASE, Cuba -- The imposing steel and concrete building known here as Camp 6 once was the bane of Guantánamo detainees and human rights groups alike.

Built in 2005 for $38 million, it was a grim collection of darkened cellblocks where detainees were locked into their cells most days for 22 hours. Food was passed to the captives through a slot in the steel door, and guards peered inside every three minutes, to make sure none had hanged themselves. Lawyers said the rugged regime amounted to solitary confinement and drove the detainees mad.

Now, however, Camp 6 has become the lockup of choice for captives. Inmates can lounge in the cellblock, watching big screen televisions or chatting with each other. Meals, delivered in bulk, are parceled out by the detainees themselves and leftovers are stashed in a pantry in case a detainee feels the urge.

Perhaps most important, say military officers, when a detainee tires, he can retreat to his private cell and close the door.

It's the guards now who are confined to cages, small enclosures at the edge of each cellblock where they watch detainees, but rarely have the need to be in close physical proximity.

"It's the privacy factor,'' said Army Lt. Col. Andrew McManus, a senior commander, explaining why Camp 6 now houses half of Guantánamo's 174 detainees.

Life in the camp began changing, incrementally, across the first year of the Obama presidency even before the White House ordered the Pentagon to make sure the controversial prison camps were in compliance with the Geneva Conventions that govern how war prisoners are held and treated.

Contractors began tearing down row after row of chain link fencing that was welded into the building as a crude improvisation after disturbances swept through Camp Big Sky on the heels of rumors that guards were going to shake down the prisoners' Qurans.

Retrofitting now reflects the military's acknowledgment of years of captives' complaints: Workers are dangling soundproofing material in the rafters, to try to muffle the warehouse style effect that makes conversation echo throughout the cellblocks.

Recent visits at Camp 6 showed most cell doors open, captives at stainless steel picnic tables watching giant flat-screen TVs, picking through leftovers in a cell-turned-food pantry, doing laundry in a sink and studying Qurans cross-legged on a mat.

Captives have to a degree sorted themselves out by their entertainment tastes, McManus said. Men who don't mind seeing women on TV are in one block, religious conservatives who only want to hear the chant of a Quran in another.

One cellblock, Golf, got a PlayStation recently. Charlie block, made up mostly of young Yemenis, is considered the most fanatic -- for soccer.

Military officials said they have consciously attempted to make Camp 6 feel more like a dorm and less like a SuperMax for the men, most held for eight years and all without charge or trial.

The detainees began asking in earnest to be moved to the building they once loathed this summer after a succession of tropical storms had guards ordering captives into their bunkhouses to avoid lightning strikes at the former favorite, an open-air prison known as Camp 4. Some captives call it the Big Sky Camp. There, the detainees also live in a communal setting, have access to the open air 20 hours a day and share sleeping quarters.