The Pentagon has built a series of facilities at Guantánamo Bay since it inaugurated its offshore detention and interrogation center for terrorist suspects in January 2002 by airlifting captives to remote Cuba from Bagram, Afghanistan. In early 2011, House Armed Services Committee chairman, Rep. Buck McKeon, R-Calif., declared the prison camp infrastructure had an overall capacity to confine 800 captives. Here's a breakdown of the known lockups and other buildings, with best estimates of the current detainee population:

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Camp X-Ray: The first camp, with 311 cells made of chain-link fencing, has emerged as the iconic image of the rugged, makeshift accommodations granted so-called enemy combatants in remote Cuba. A maze of kennel-like cages, the camp housed prisoners for about four months. It was an arrangement that allowed them to chat and pray communally and at one point organize the first hunger strike. One captive's leaked interrogation log indicated it was used even after it was closed for the "enhanced interrogation techniques" used on Mohammed Qahtani, a Saudi whom a senior Pentagon lawyer declared was tortured in U.S. custody. Now abandoned, and overgrown with weeds, it provides journalists from around the world an opportunity to see how the detention center's infrastructure has evolved. Opened: Jan. 11, 2002. Current population: zero.

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Camp Delta, also known as Camps 1-2-3: This was the first improvement for housing the detainees. Halliburton workers from the Indian subcontinent welded metal shipping containers to create about 720 individual steel and mesh cells in boxcar-style arrangements. Built in stages for well over $30 million, its first phase, built in May 2002 with a projected five-year life span, has been renovated to make it harder for captives to rip steel parts from the walls and floors of the cells. In June 2006, three Arab captives were simultaneously discovered hanging in their cells, initially unnoticed by guards because they hung towels to block the view. By January 2009, a Pentagon report said, it was being used to house an undisclosed number of hunger-striking detainees being force-fed nutritional shakes through tubes tethered up their noses and into their stomachs. In recent years, it was used to jail detainees considered leaders or troublemakers in a special section called One-Alpha, men the military believed could influence other captives. Opened: April 28, 2002. Current detainee population: Zero.

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Camp Echo: The military uses this 24-cell camp as a segregation site for captives who can't mix with others, notably those who are cooperating with their captors. It has also been used for captives to meet lawyers inside shed-style buildings containing a tiny cell, a toilet and shower, with adjoining space for a table and chairs, and an ankle shackle fixed to the floor. Until a federal judge ordered the practice halted in November 2004, it was used as a special segregation site for detainees facing war-crimes trials before Military Commissions. Confessed al Qaeda foot soldier David Hicks of Australia lived there on and off for long stretches of his five-year stay at Guantánamo and was segregated from the "enemy combatant" population following his guilty plea while awaiting repatriation to his homeland. In April 2013, a prison camps spokesman, Army Lt. Col. Samuel House, said the detention center considered captives held there to living communally. Opened: Date unknown. Current detainee population: At least five.

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Camp 4: Meant to be a showcase, pre-release detention area for 175 or so of the most cooperative, least dangerous captives, it was designed to resemble a traditional prisoner-of-war lockup. It has 10-cot bunkhouses, communal showers and toilets and a common outdoor eating area with picnic tables where captives could pray together. Commanders also added exercise bicycles and let play pickup soccer beneath a watchtower in "The Big Sky Camp," as captives called it for its open-air spaces. In May 2006, it was the scene of what guards described as a foiled uprising in May 2006 but later had a classroom with desks and leg shackles for Arabic, Pashto and art classes as well as a satellite TV trailer. The military emptied the camps in January 2011 for repairs but by Sept. 11, 2011 it was out of service -- a vacant, rusting compound used by the BBC to broadcast a two-hour program back to Britain. By then, President Barack Obama's Jan. 11, 2009 closure order, complete with his sweeping signature, could be plainly seen fading on detainee bulletin boards where guards had hung it soon after the commander in chief signed it. Opened: February 2003. Current detainee population: Zero.

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Camp 5: A maximum-security building modeled after a state prison in Bunker Hill, Ind., the $17 million building and adjacent disciplinary block can house 124 captives monitored by guards using closed-circuit cameras and a central locking system. The main building has special interrogation cells, outfitted with faux Persian carpets, blue velour reclining chairs with an ankle shackle point, monitors, panic buttons and open-air, cage-like recreation areas. It has in the past housed 100 prisoners considered of greatest intelligence value, each in a single cell with toilet and fixed sleeping shelf under constant monitor by guards who peer through their windows. A top tier block in the building is being used as a "Convicts Corridor" to segregate two captives who've been convicted of war crimes at a Military Commission. Each detainee gets his meals slid through a slot in the metal door, and can exercise in a chain-link fence encircled recreation yard. In the summer of 2011, at least one prisoner smeared his excrement in his cell ventilation shafts, sending a stench through the structure that sickened both captives and guards. Commanders claimed it ended some months later due to peer pressure. By 2013, the military had designated Delta Block as a communal lockup, according to attorneys, where captives on the 10-cell corridor were allowed to mix and mingle rather than be locked inside their cells. Guards watched from the outside, while captives had access to a small kitchen, recreation yard and satellite TV room. Opened: May 2004. Current captive population: About 80.

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Camp 5 Echo: The prison's disciplinary block, this 24-unit boxcar-style lockup attached to Camp 5 has steel plates rather than metal mesh welded between cells in conditions captives and their lawyers likened to abusive isolation. It was built in November 2007 at a cost of $690,000, according to Navy Cmdr. Tamsen Reese, who as prison spokeswoman in late 2011 released the first-ever photo of the segregation site, at right. It is not shown to reporters invited to the remote Navy base for prison camps tours that boast a safe, humane and transparent approach to U.S. military detention. "Typically," according to Reese, the segregation site "serves as a disciplinary block for those non-compliant detainees in Camps Five and Six. Discipline is administered through a process of reduced levels of privileges, and not by use of isolation or solitary confinement." It is not known when the prison sealed up the cells. Navy Vice Adm. Patrick Walsh, finding the camps compliant with the Geneva Conventions in February 2009, described it as "an open air facility with 24 individual adjoining steel mesh cells arranged in two parallel and equal rows – similar to Camp 1." Opened: April 2008. Current detainee population: Undisclosed.

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Camp Five Physical Therapy Building: Little is known about this structure, which is also not on the tour of facilities where captives are kept at the detention center compounds. Navy Cmdr. Tamsen Reese, speaking for the prison, said it was built in August 2009 for $442,105 as a "detainee learning center." Its existence was revealed in 2011 when the Southern Command in Miami notified members of Congress that it planned to remodel it to function as the main prison hospital. At the detention center, plans for the future hospital involve the Physical Therapy building functioning as a "center infirmary hub," with a small number of "satellite expeditionary medical shelters" surrounding it. Opened: Date unknown. Current detainee population: Unknown.

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Camp 6: This $39 million, centrally run, 200-cell prison with 175 beds welded to the walls was meant to be a minimum-security, all-enclosed version of Camp 4, with communal eating areas, easy-access showers and its own medical and dental clinic based on a Michigan model. After detainees fought guards inside Camp 4 in May 2006, it was redesigned as a maximum-security lockup where captives ate every meal and spent at least 22 hours a day inside single-occupancy 6.8-by-12-foot cells furnished with a stainless steel sink and toilet, a bunk and a steel desk with a slot to hold each captive's Quran. A common recreation yard was subdivided into five chain-link-fence-style cages. By August 2010, the military said detainees were back to living collectively there, with up to 20 hours a day of TV or radio broadcast through headsets. Commanders said each of the 22-cell pods was organized according to broadcast preference with two pods having exclusively Quranic radio broadcasts from Saudi Arabia. Another was made up predominantly of Yemeni soccer fans who dominated in matches in the communal recreation yard. Afghan Awal Gul, 48, collapsed and died in one cellblock after working out on an elliptical machine Feb. 2, 2011. On May 18, 2011, guards spotted another Afghan, Hajji Nassim, hanging from bed linen in a recreation yard early one morning in what was considered the sixth suicide of the detention center nearly decade long existence. On Feb. 28, 2012 the camps' public affairs team showed reporters a two-toned gravel field surrounded by fences and barbed wire to reveal a $744,000 soccer field there, called the "Super Rec," for recreation. On April 13, 2013, the Southern Command said troops raided the communal blocks, fought with captives who resisted them and locked each of 60 men one by one in single cells. Opened: December 2006. Current detainee population: About 60

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Camp 7: Little is known about this secret camp within the camps, whose existence was revealed Dec. 8, 2007, in declassified notes of the first attorneys to meet former CIA-held captives. The Pentagon refuses to say how much taxpayers paid to build it, when it went up and what firm got the contract. The camp is not on the media tours that boast safe, humane, transparent care and custody of the 166 foreign captives but members of Congress sometimes get to stop in and look at the prisoners through one-way glass. An Army colonel who runs the other portions of the prison at Guantánamo has said he has oversight of the special unit that runs it, Task Force Platinum. In February 2013, according to war court testimony, soldiers were replacing sailors as guards inside the secret compound. In February 2009, then Vice Adm. Patrick Walsh visited the camp and described it as similar to a "SuperMax" prison in the United States -- with climate controlled cells, a recreation yard surrounded by a chain-link fence and rooms where detainees can watch videos and play with hand-held games. It also has can provide dental services so ex-CIA captives need not be taken to the main detainee medical facility. Only one Camp 7 detainee has been known to ever leave detention there: Tanzanian Ahmed Ghailani, who on June 9, 2009 was sent to New York and convicted at a federal criminal trial. Baltimore-raised Pakistani Majid Khan, who pleaded guilty to war crimes on Feb. 29, 2012, was segregated from the others at Camp 7 in an annex situation similar to the Convicts Corridor at Camp 5, according to Rear Adm. David B. Woods. There are no known pictures of the place but the confessed 9/11 mastermind, Khalid Sheik Mohammed has posed for Red Cross photos inside there that leaked to the internet. The prison's staff attorney disclosed at a November 2011 war court hearing that it has multiple tiers that separates KSM from the alleged USS Cole bomber, Abd al Rahim al Nashiri. The CIA has acknowledged that its agents waterboarded both men. Opened: Date unknown. Cost: Pentagon declines to disclose. Current detainee population: 14

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Camp Iguana: It was initially established as a segregated housing compound for pre-teen "enemy combatants" flown in from the war zone, and had a single building. Since then, contractors and sailors have added a series of huts -- first for meetings between captives and their lawyers, later as a lockup for men whose detention was ruled unlawful by the federal courts. It now houses three ethnic Uighur Muslims from China behind razor wire topped chain-linked fences that separate guards from prisoners and has a series of wooden huts and a wash house where, commanders have said, up to 20 detainees can get greater privileges, including more phone calls, a prayer room, a Wii and a view of the Caribbean. Commanders have briefed that Camp Iguana captives at times were allowed to order fast food.Opened: Date unknown. Current population: Three.

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Behavioral Health Unit: The prison's psychiatric ward is a separate building adjacent to the detention center hospital, both run by U.S. Navy medical professionals who come and go on rotations of generally less than a year. The BHU, as the psych ward is known, serves as a segregation site for captives removed from the general population with diagnoses of mental illness or "self-injurious behavior." There's been no suggestion that any of the former CIA prisoners, in the custody of Task Force Platinum, have been treated there. The Behavioral Health Unit can hold up to 12 detainees in special single-occupancy cells, ostensibly under constant surveillance. A Yemeni captive died in his cell there in the summer of 2009 in what military investigators concluded was a suicide. Reporters on media visits pass by it on their way to a detention center hospital briefing, but are forbidden to look inside. Opened: 2006. Population: Four captives as of April 17, 2013.

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Detention Center Headquarters: The prison's senior staff work at the Intelligence Operations Facility, or IOF, the command and control center for the 1,700-1,800 military and contract workers at the detention center complex that today houses 171 foreign men as captives. The state-of-the-art building known as the Red Roof Inn was built in 2004 for $13.5 million. It's not far from the entrance to the now defunct Camps 1-2-3, and even closer to the Seaside Galley dining facility for prison staff where the captives' meals are also prepared. The commander and his deputies occupy space in this eavesdrop-proof structure, the best and most technologically equipped building at the Navy base on a space far from the downtown at the site called Radio Range. It has teleconferencing, the staff judge advocate and public affairs offices. Based on testimony at the war court's Camp Justice compound, miles away, it also receives a live feed of military commissions proceedings so the jailers can monitor testimony and arguments in the cases against their captives. Opened: 2004.

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updated May 6, 2013
Carol Rosenberg, Miami Herald