It is the strangest travel trend yet.
A global fascination with tragedy has turned some of history's darkest moments into popular tourist attractions.
Places like Ground Zero, Auschwitz and Alcatraz attract thousands of visitors a year in a trend known as "dark tourism"
In 2016, the World Trade Centre memorial was the subject of more than 62,000 TripAdvisor reviews with 54 per cent rating the site where close to 3000 people lost their lives, as "excellent".
The Tower of London with its enduring reputation as a place of torture and death was the second most reviewed site, followed by Ann Frank House in Amsterdam where the young Ann and her family hid from the Nazis in World War II.
Australia's most reviewed dark tourism site was Port Arthur where Martin Bryant gunned down 35 people in 1996.
Dr Elizabeth Grant who contributed to the Palgrave Handbook of Prison Tourism coming out this month, said the term "dark tourism" was actually coined when people started visiting the scene of John F Kennedy's assassination in Dallas.
"People started taking pictures of that site in Dallas and if you see their behaviour when they go there, it's really quite strange," said Dr Grant.
"It's like they're getting a trophy shot."
She said the same was true of the Auschwitz concentration camp, Pearl Harbor and the electric chair at the Texas Prison Museum.
"Some people like the sinister, and like the macabre," Dr Grant said.
"It can seem like we're becoming more obsessed about a quick personal experience in gathering places rather than understanding the place."
Handbook Editor Jacqueline Wilson said prison tourism was emerging as one of the most popular forms of tourism in the world.
"Some times these places are just so terrible the only way people can deal with them is to have a laugh," said Associate Professor Wilson.
"I can understand the selfies with the noose and the keystone cops tourist guides - why there's that aspect."
Travel enthusiast Ben Alcock said he never planned a holiday specifically for the purpose of visiting a "dark tourism" site but he had visited many including Ground Zero, Anzac Cove, Tiananmen Square, and the Killing Fields in Phnom Penh.
"Sometimes being close to the deep melancholy of a place connected to tragedy can arouse a morbid thrill, a shiver of ghastliness," Mr Alcock said.
"The same thing we might feel watching a horror film, only real."
Insurance expert with finder.com.au Bessie Hassan said the number of reviews posted online about the dark tourism sites showed travellers were keen to share their "haunted holiday stories".
"People are generally intrigued by places with negative or tragic histories, and are naturally drawn towards them, but you wouldn't typically expect responses to be so positive," said Ms Hassan.