After more than $700 million and years of delay, the National September 11 Memorial Museum opened on Wednesday in downtown New York.
To enter this museum, you pass through a soaring glass pavillion, complete with two structural "tridents" rescued from the twin towers.
Then you descend into subterranean galleries, "a crypt beneath a crime scene," as Justin Davidson phrased it.
Tucked in the bowels of the World Trade Centre site are multimedia displays, mangled artifacts, and a medical examiner's office, holding the remains of more than 1000 unidentified bodies.
There is also a gift shop.
Early reactions to the Memorial Museum have ranged from sober appreciation to emotional hostility.
At the negative end of things, people have objected to the US$24 (NZ$28) admission charge, to an out-of-context Virgil quote written on the wall, to the entombed human remains, and to the gift shop merchandise (hoodies, mugs, a rescue vest for dogs).
"This tchotchke store - this building, this experience - is nothing more than the logical endpoint for our most reliably commodifiable national tragedy," snapped Buzzfeed's Steve Kandell, who lost his sister in the terrorist attacks.
"If you want to bring a coffee table book full of photos of cadaver dogs sniffing through smoking rubble back home to wherever you're from, hey, that's great."
But the fact is that September 11 Memorial Museum is just the latest example of a growing genre of tourist attractions - a genre that raises difficult questions about ethical propriety and our own impulses as travellers.
It is no surprise, for example, that the woman brought on to curate the Memorial Museum, Alice Greenwald, was previously a director at the Holocaust Museum in Washington DC.
There is an affinity between the two institutions, both designed to catalogue brutal acts of terror in extraordinary detail.
Sites marking the Holocaust can be found everywhere from Brazil to Bulgaria, and some of them - like the Memorial to the Murdered Jews of Europe, in Berlin - attract sizeable visitor numbers.
Then there are the the camps themselves, like Auschwitz-Birkenau, now a memorial and museum where one can wander through the cell blocks and into the chambers where the Nazi's released Zyklon B gas, exterminating millions.
In Rwanda, one can visit Nyamata Church, where 10,000 Tutsis were murdered by the Interahamwe on April 10, 1994. "Although the remains have been removed, bones still peek out of the clothing [piled up on pews]; a rib here, a vertebrae there," explains the visitors website.
In Cambodia, tourists flock to the Killing Fields; and in Japan, there is Hiroshima. We seem to take particular fascination in places of extreme brutality.
But why? As New York kvetches about the opening of this new, near-unclassifiable attraction, I find myself wondering: What is the purpose of these sites?
On one level, of course, they are living proof: This happened. The tide of history is very strong, and memory erodes fast; for the same reason we say "lest we forget" on Anzac Day, these sites memorialise the dead.
They also illustrate events that otherwise exceed our imaginative capacity (six million jews is impossible to picture; a pile of abandoned luggage at Auschwitz is effectively devastating, though).
But rubbernecking is a basic human impulse, too. These places can shift, surprisingly quickly, into more dubious terrain.
One can just as readily ask why we need to see the machete-scored skulls in Nyamata Church - or, for 9/11, racks of perfectly preserved shirts covered in ash, and a wristwatch from a passenger on ill-fated Flight 93.
Do these objects really deepen our understanding of the tragedies? Or are they fetishisistic, allowing us to brush against the darkness and then resurface, feeling safe, perhaps with a souvenir?
Perhaps that's an uncomfortable idea. But part of what makes the National September 11 Memorial Museum so controversial is its amalgamation of two things: a memorial, which is about laying to rest and solemnly commemorating; and a museum, which is about anatomising something and breaking it down, minute-by-minute, for a million curious eyes.
I toured the museum in 2011, at which point only a few of the larger artifacts had been installed. One of these pieces was a fragment of staircase - "The Survivor Stairs," they were being called - which a lucky few had managed to flee down before the towers collapsed.
It was cordoned off beside a second, functioning staircase, sort of like a dark mirror image, and I was encouraged to pause and appreciate the concrete assemblage.
I didn't understand it. Was I meant to feel bad (which I did), or was I meant to visualise the panic and carnage and abject fear of that horrible day?
What is the value of that? What is the value of touching Nazi ovens, or eyeballing a blood-stained altar in a desecrated African church? What, as travellers, are we hoping to find in these places?
- FFX Aus