The razor wire tumbles from the chain link fences and the only signs of life come from insects and birds. The wooden ladders up to the guard towers are rotting away.

But the outdoor prison camp remains instantly recognisable. Over a decade ago photos of detainees in orange jump suits – cuffed, hooded and masked – kneeling at the feet of US soldiers in this outdoor passageway became emblematic of how the United States intended to fight its new war.

A small group of US soldiers leads Fairfax Media through the complex. We inspect the wire and steel cages that the first detainees to arrive Guantanamo Bay were held in. Each is a cube of less than 2.5 meters square sitting on bare concrete. A fat banana rat – named for the shape of its dung rather than for its diet – skitters across the mesh roof.

Guided by a young army reserve captain from Arizona, we wade through the grass between coils of rusted barbed wire.

This pathway was once famous too. This was where photos were shot of detainees being wheeled on stretchers from the cages to the interrogation rooms . Somehow those stretchers made the whole scene more awful.

The captain – who like all but the most senior officers at Guantanamo cannot be named – puts the image into context. Protocol dictated that outside their cages the detainees could never be unshackled outside the cells, she explains.

The short walk to the interrogation sheds left their skin chaffed so the soldiers wheeled them on the stretcher instead. After the photos of the bound men being ferried to and from interrogation on stretchers provoked international outrage they started using a golf cart.

The plywood sheds are curling and rotting in the tropical conditions, and in their decay they remain claustrophobic. Each contains two or three rooms, some with wooden benches and tables still in place.

X-Ray was used to house detainees for only four months from January 2002 while more permanent facilities were being built elsewhere on the base. Asked why it still stands, the captain explains that demolishing it may make it look as though America had something to hide. Days later she will add that due to the amount of legal action pending over the site, the military's Southern Command ordered it be preserved.

Like most of the 2150-odd soldiers deployed to the detention centre known as Joint Task Force-Guantanamo, the captain is new to the place. Most of the units rotate in for a 9-month tour. She says she knew little about the detention centre before her training for this deployment, but had heard bad things.

Now she here she feels differently.

"The thing about Gitmo," she says, "is that it is just kind of boring." Rather than finding a hellhole when she arrived she said she found, "American soldiers acting the way American soldiers do, humanely". That, she says, was comforting.

Not far from X-Ray, 136 detainees are still being held in two other facilities. About half of them have been cleared for release since 2010, but the papers that need to be signed remained held up by the Pentagon, despite pressure from the State Department.

Some of these are thought to be innocent of terrorism, others are thought to be little more than Taliban footsoldiers.

Others are known as the "forever prisoners", 36 men who will be neither tried nor released, and thought to include Khalid Sheik Mohammed, the self-proclaimed mastermind of the September 11 attacks.

To get to these camps you drive through a checkpoint and past a sign that on the first day of our visit proudly proclaimed, "Joint Task Force Guantanamo. Think Before You Drink. 9 Days Since The Last Alcohol Related Incident."

Beyond the checkpoint is a sprawling complex. Camps 5 and 6, where the detainees are held, are imposing buildings, indistinguishable from a modern supermax prison.

There are barracks, a chow hall, a multi-storey headquarters, a medical facility that is being expanded and updated so it can treat the diseases of a small but aging population, ailments like diabetes and heart disease.

On a nearby bluff above the bright blue Caribbean Sea sits Camp Iguana, where three children were once held, and below it a beach where civilians and off-duty military personnel sunbathe on lounges and snorkel over the coral.

Six years after President Obama vowed to close Gitmo it appears ever more permanent, even as its detainee population declines. And it has become the centre of one of the last great battles to be waged between Obama and the resurgent Republicans in Congress.

Obama views the camp as not only expensive, but a blight on the nation's international standing, evidence of mistakes and overreactions in the febrile days after the September 11 attacks.

Republicans tend not to view the early years of the war on terrorism as critically. Many remember them as George W. Bush described them, a time when grief turned to righteous anger and then resolve.

Either way the decisions made in those days have made these prisons unique in the world, and uniquely difficult to close.

Many of those detained within the camps are survivors of the CIA's international network of secret prisons, and the torture that was conducted within them as revealed so chillingly in the US Senate report this week.

As a result of the abuse, evidence against the  "forever prisoners" is tainted.

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The prison camps at Guantanamo Bay were born of the same quiet policy decisions that led to America adopting torture as a tool of the war on terrorism. On September 17, 2001, before America had even counted all of its dead, George W. Bush ordered the CIA director to "undertake operations designed to capture and detain persons who pose a continuing, serious threat of violence or death to US persons and interests or who are planning terrorist activities."

On November 13, Bush ordered the Pentagon to hold captives indefinitely, without charge and without any right to challenge their detention in a US or international court. On November 26, CIA lawyers circulated a draft memo arguing the torturing of captives was legal because it proved necessary "to prevent imminent, significant, physical harm to persons, where there is no other available means to prevent the harm."

As the Senate Intelligence Committee released earlier this week revealed, the CIA was soon holding and allegedly torturing captives in "black sites" around the world.

If these were spokes, the wheel needed a hub – a place where many detainees could be held securely in the long term, far from prying media eyes, and more importantly, from legal protection.

The US Naval base at Guantanamo appears to have been first proposed in a November 2001 memo by the CIA's head of counterterrorism, Cofer Black, called Approval to Establish a Detention Facility for Terrorists.

The memo urged to the agency's director, George Tenet, to press the Pentagon "at the highest levels to have the U.S. Military agree to host a long-term facility, and have them identify an agreeable location." The memo recommended that Tenet request "to have the US Naval Base at Guantanamo Bay designated as a long-term detention facility."

Guantanamo seemed perfect. A secure base in Cuba, it was arguably outside the jurisdiction of US courts, but close enough for easy travel from the mainland. Better yet, the cages of Camp X-Ray had already been built years earlier to house criminal elements of a mass immigration from Haiti.

In January 2002, the first detainees were flown in from Afghanistan.

"Guantanamo was the epicentre of what became the de facto US posture that it was permissible, even preferable, to detain any and all people who conceivably might have connections to our enemies," says a report by a bipartisan group called the Constitution Project. The Detainee Treatment report was written by a committee chaired by politicians of both parties, a former FBI director, a former president of the American Bar Association, leading legal academics and a former three-star general.

"Although it was never stated explicitly, senior officials thought it better to detain any number of innocent people than to run the risk of setting free anyone who might be a threat," the report states.

According to Alka Pradhan, a lawyer who worked on the report and now represents several Gitmo's detainees, the savage interrogation techniques developed and deployed by the CIA – including sleep deprivation, beatings, stress positions and waterboarding – quickly spread to other branches of the US government, and were soon being used by army interrogators at work in the wooden sheds that Fairfax Media visited last week.

While the first detainees were being held at X-Ray, the military went about building more substantial facilities. Conditions improved somewhat when Camp Delta, which at least had demountable huts, opened.

Today the remaining detainees are held in Camps 5, 6 and 7.

In Camp 5 so-called non-compliant prisoners are held in isolation in a supermax panopticon-style prison. In camp 6 compliant prisoners have single cells but are free to spend most of their day in a common area with access to an exercise yard. The military refused to even acknowledge the existence of Camp 7 until recently, and only a handful of so-called "high-value" detainees are kept there.

There have been other changes. In 2008 the Supreme Court finally struck down the Bush administration's claim that the detainees were beyond legal reach, declaring, "In every practical sense, Guantanamo is not abroad." For the first time, the detainees had access to outside legal assistance.

There have been other changes too. Since lawyers forced the gates open the US military has sought to improve its image by allowing highly supervised visits by media.

To get there you take a charter flight from Miami and, from the base's naval air station, a ferry to what is in effect the main street of an American town of around 5000.

We arrived in a warm sunset with dance music blaring over the speakers of the boat.

As a reporter, you are never left alone on base, and normally you are escorted by a small party of guides – one of whom is assigned as "sweeper", walking along behind the main group to ensure no one slips away. Fairfax Media visited with just one other reporter, so while friendly, the scrutiny was intense.

The four-day tour included visits to various base facilities, as well as to camps 5 and 6, along with interviews with senior officers.

The current Joint Task Force commander is Rear Admiral Kyle Cozad, a pilot rather than a jailer by training and experience. He easily parries questions about the camp and its treatment of detainees. His mission, he says, is to provide just, safe, humane and transparent detention.

He believes, he says, that the long-term detention of people who have not been tried for a crime is just by the rules of war.

He  seems not to know of any abuse before his time, and is certain there has been none since he arrived.

Army Colonel David Heath took over command of the task force's guard unit last year. He too says he is certain that no abuse has occurred under his command, and that he has seen no evidence that it occurred here in the past.

Many questions you ask at Gitmo are answered this way. "That was before my time," they say.

In 2013 – before Cozad and Heath's time - a group of inmates became so dispirited at their apparently endless detention that a widespread hunger strike began. Some detainees began flinging faeces and urine at guards too, a practice known here as "splashing".

According to Pradhan, the hunger strike succeeded in renewing international attention on Gitmo and embarrassing the administration and the military that managed it. At first, officials described the protest as an al-Qaeda tactic of "asymmetrical warfare". That euphemism appears to have fallen away now, and when Fairfax Media visited it was generally referred to as "prolonged non-religious fasting".

Either way the US did not want any more of the detainees dying (nine have died since the camps opened) and soon they began a force-feeding program that some describe as illegal, and also akin to torture.

Pradhan says the force-feeding is transparently "punitive". Each session, she says, begins with a "forcible cell extraction team" in riot gear removing the detainee violently, before he is strapped down for the procedure.

One of her clients, she says, was overfed to such an extent that his stomach was distended and he was caused excruciating pain.

Another, released to Uruguay days after Fairfax Media's visit, is now in hospital recovering from the medical treatment he received on the island, Pradhan says. His back was injured in interrogations and when his protest began, his wheelchair was removed, she says.

We are guided through the camp's medical centre to inspect a force-feeding chair. With its straps and harnesses, it vaguely resembles something you might use for an execution.

The chief medical officer describes the practice in medical terms. She said her team does it with "precision and pride".

Asked about a navy lieutenant who last year was almost court martialled for refusing to assist in the practice, she says that the incident was before her time.

Eventually we are guided into an empty wing of Camps 5 and then into 6. Surrounded by around 20 military personnel, we peer for a few minutes through a tinted window into a common area of Camp 5. It looks humane enough. It looks as comfortable as a high-security prison could be. A few men in pajama-like uniforms watch TV and shuffle about.

But it is impossible, perched in silence and in darkness so as to not give away our presence, and surrounded by around 20 military personnel, to get a sense of life at Guantanamo for detainees.

Even the guards do it tough says Pradhan, citing evidence of high rates of depression and alcoholism among the units who, rotate through every nine months. Every notice board I saw on the base had posters warning of the dangers of alcohol abuse and encouraging people to report sexual assault.

Those soldiers who were allowed to speak with us universally voiced dedication to "the mission" and pride in their work. Most noted that there were many US soldiers around the world in far worse circumstances. Though separated from their families, the soldiers at Gitmo enjoy beaches and sports teams, an outdoor cinema, McDonalds and Subway, even an Irish pub.

It was here on our last night that without supervision I met a sergeant with a Ranger unit deployed for base perimeter security in the unlikely event of an attack by the Cuban military.

After four combat deployments during which he has been shot, burnt and blown up, this is by far his worst, he says. Life on a secure base bores him and makes him nervous. Over there, he says, "All you have to do is find them and kill them. I don't know what to do here, I don't know how to do this."

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In a sense, America is as captive of Gitmo as its detainees. Colonel Heath has no idea when the facility may finally be mothballed.

"I will operate the camps until either I am ordered to close them or until I am ordered to leave and turn it over to another colonel," he says.

That is looking increasingly likely, even though no new detainee has arrived since 2008.

On January 22, 2009, shortly after taking office, President Barack Obama signed an executive order calling for the closure of the detention centrewithin a year, saying the United States does not have "to continue with a false choice between our safety and our ideals." Republicans in Congress refused to co-operate. In December 2009, Obama signed an order calling for the government to acquire an Illinois state prison as a site for holding Guantanamo Bay detainees, but in May 2010, Congress blocked funding for that prison and for any future replacement facilities in the United States.

Speaking after the release of the Senate's report on Tuesday, Senator John McCain, said torture had stained America's national honour. Whatever occurred here, Guantanamo has become symbolic of that torture. Obama himself has described Gitmo as a terrorist recruitment tool.

It can't be an accident that Islamic State militants have taken to dressing their victims in the Gitmo's orange jumpsuits before it beheads them.

Back in the Irish pub, the bored Ranger, who like most people on the base has never laid eyes on a detainee, pays them little mind.

"I don't care what they do with them. Send them home or shoot them in the head. I do not care."