Tuol Sleng is a name, like Auschwitz or the Gulag, which should strike horror into the heart.
Tuol Sleng was the prison where the Khmer Rouge took Cambodians unfortunate enough to have fallen afoul of the regime, perhaps because they had a medical qualification, or in some cases merely because they could read.
Tens of thousands went into Tuol Sleng - otherwise known as S-21. Very few came out.
But before they died, they were tortured.
I remember going into Tuol Sleng in 1991, filming for Four Corners during the UN transition period that brought Cambodia back into the family of nations.
The cells were tiny and dark, and it was not hard to imagine the suffering of the people who were incarcerated there for reasons which they were never given and which were in any case absurd.
One of the tortures they were subjected to was called waterboarding.
A prisoner turned painter, Vann Nath, depicted waterboarding in a series of paintings on the walls of Tuol Sleng, which is now a genocide museum.
Back then - nearly 20 years ago - the civilised world was horrified and revolted by the revelations of what the Khmer Rouge had done, including waterboarding.
But this week, George W Bush has asserted that waterboarding is not torture.
"Let's talk about waterboarding," he says to NBC's Matt Lauer, who asks: "Why is waterboarding legal?"
Bush's answer? "Because the lawyer said it's legal."
So, Lauer continues, "Would it be OK for a foreign country to waterboard an American?"
To which Bush only replies that people should "read the book".
I haven't had a chance to follow the former president's advice and read Decision Points, but from what I've read it doesn't contain any more sophisticated defence of waterboarding than "the lawyer said it's legal".
From what's emerged in the last year or so, it's clear, though, that Bush himself was not the driving force in allowing waterboarding.
That was his vice-president Dick Cheney, who said in February of this year: "I was a big supporter of waterboarding."
The rationale was that waterboarding - defined as torture around the world - was not only legal but necessary to prevent another 9/11.
We know now that the 9/11 mastermind, Khalid Sheikh Mohammed, was waterboarded 183 times in one month.
Bush writes that this was necessary, and that the torture provided useful information.
The interrogations ... "Helped break up plots to attack American diplomatic facilities abroad, Heathrow Airport, and Canary Wharf in London, and multiple targets in the United States."
But now Mr Bush's erstwhile allies in Britain are denying that, as the Guardian reports:
"British officials said today there was no evidence to support claims by George Bush, the former US president, that information extracted by "waterboarding" saved British lives by foiling attacks on Heathrow Airport and Canary Wharf."
Many studies have confirmed what common sense should suggest: that torture is an extremely inefficient way of getting information.
Under enough torture (and 183 waterboardings in a month is a good deal more than enough), the target will confess to anything. And if you intend eventually to try the prisoner in a court, the torture itself is likely to invalidate the case.
This remains a danger in the case of Khalid Sheikh Mohammed. Few doubt that he is guilty of plotting the attacks on the Twin Towers and the Pentagon, but there's real fear that a guilty verdict will be hopelessly polluted by the torture factor.
And torture infects the forces that wield it.
It may have begun as a desperation measure, used by officers who genuinely felt that they were in the position of Jack Bauer in the fictional series 24, with no alternative if they were to prevent an atrocity.
But, once begun, it grew and grew.
What we know now, from declassified documents, is that the CIA's waterboarding became systematic and programmed, planned and recorded in gruesome detail.
The CIA used a "specially designed" gurney for waterboarding. After immobilising a prisoner by strapping him down, interrogators then tilted the gurney to a 10-15 degree downward angle, with the detainee's head at the lower end. They put a black cloth over his face and poured water, or saline, from a height of six to 18 inches, documents show. The slant of the gurney helped drive the water more directly into the prisoner's nose and mouth. But the gurney could also be tilted upright quickly, in the event the prisoner stopped breathing.
Interrogators were instructed to pour the water when a detainee had just exhaled so that he would inhale during the pour. An interrogator was also allowed to force the water down a detainee's mouth and nose using his hands. "The interrogator may cup his hands around the detainee's nose and mouth to dam the runoff," the Bradbury memo notes. "In which case it would not be possible for the detainee to breathe during the application of the water."
If this wasn't enough, the Bush administration's lawyers said the CIA could combine it with other forms of torture - depriving the prisoner of sleep for more than seven days straight, physically slamming him into a wall, cramming him into a small box, placing him in "stress positions" to increase discomfort and dousing him with cold water, among other things.
It's unlikely anyone will be brought to justice because of all this, though.
That's partly because the CIA was allowed to destroy much of the evidence, in the form of videotapes, of the torture it committed.
And even the people who destroyed the evidence won't be punished. Just as ex-president Bush was plugging his book, the justice department announced that no charges would be brought against the CIA officers who got rid of the tapes.
The consequences of all this are many, and they don't just affect America.
Those who went to war with the US in Iraq and Afghanistan risk the problem of guilt by association, as Britain's David Cameron has been finding out in China this week.
China, under attack of its jailing of a Nobel Peace Prize winner, feels free to attack its accusers for hypocrisy.
Winston Churchill, at the darkest hour of the 20th century, with his entire nation at risk, refused to countenance the torture of Nazi prisoners.
He believed that above all, it was important not to become that which we were fighting against.
It's a precept Western democracies should remember, and return to immediately.
I think the last three sentences sum it up pretty damn well.