Beaten, hog-tied and deprived even of being able to pray - former Guantanamo Bay detainee Shaker Aamer has told ITV News what he says life was like inside the notorious camp.
Subjected to "humiliation after humiliation", Mr Aamer said he is convinced that the camp was designed by psychologists, "built on how to destroy a human being totally."
Mr Aamer spent almost 14 years in Guantanamo without ever being charged.
He claimed he was subjected to regular 'forced cell extractions' - where 15 or 20 guards armed with shields would enter his 6ft by 4ft cell to remove him and terrorise him.
He said this was one of many ways the guards would use force to instill fear among the detainees.
But he told ITV News the mental torture was, for him, the worst part. "It's hard for [people] to understand ... they cannot digest that torture is not about beating, torture is not about hanging from the ceiling with handcuffs and all that," he said.
"Guantanamo is built on how to destroy a human being totally, how to damage him mentally, physically, spiritually ... it's a programme thats been designed by psychologists."
One of the devices used, he said, was to deprive them of the chance to pray.
Mr Aamer said that shortly after arriving at the base he was held in a cage in the notorious Camp X-Ray where he claims guards blasted rock music into their cells whenever they knew prayer time was approaching.
Bruce Springsteen's Born in the USA was a favoured choice, he said.
Another trick, he claimed, was to keep bright lights on the detainees at all times, confiscating anything they might use to cover their faces to go to sleep.
He is still learning to adjust to be able to sleep in darkness, he said.
Me Aamer claimed those running the camp would "prepare the scenery" before any media or officials went to visit, so nobody would realise what was actually going on.
He told ITV News:
On one occasion, he said, he was targeted by the Force Extraction Team (FET) - a kind of riot squad who would deal with problems - for keeping hold of an apple core which he wanted to use as a toothpick.
"I found myself chewing on the apple core and using it for cleaning my teeth," he said.
"So I kept the apple stem and then the guards have to ask you for it ... I refused to give it back to them.
"And for that reason that I refused this little thing, they have to call the FET team, they have to inform the watch commander, the overall sergeant, he has to reform the OIC of the camp, he has to inform the colonel, the colonel has to give him the green light to go with the FET ... Fifteen, twenty people in front of your cell because they want the apple stem."
Then, he said, they barged into his cell "like a train" and pushed him to the floor with their shields and made him lie face-down over the hole in the ground he was given as a toilet.
It was all a matter of enforcing control, he claimed.
"Their goal is to scare you, to make you submit, make you understand that if you refuse to comply with the orders it means you are going to get this punishment all the time," he said.
"They want you to submit to them, they want you to understand that they are overpowering you and you have no right to say yes or no, just do what they tell you, even if its a silly thing, a little thing like an apple stem."
He told ITV News he wants to see Guantanamo shut down for good - claiming what was going on there was a "war crime".
"Everything that happened to us is a war crime in Guantanamo. Everything that is happening right now is a war crime in Guantanamo," he said.
"When you inflict a pain on people and you make them go crazy until they kill themselves, who is who to blame?
"My message to the President of the United States [Barack] Obama ... that if he wants to be the hero, to close Guantanmo. If he really wants to establish justice, if he really wants to live by his word, he's not going to need to wait for the whole United States of America to support him.
"He should practice his right as a president, his right as the head of the army, and just close it - close it and the brothers they will help him, if you start thinking about the brothers in Guantanamo as human beings, they will help you to close it."