History’s darkest moments are being turned into popular tourist attractions thanks to a global fascination with tragedy. Places like Ground Zero, Auschwitz, and Alcatraz have been attracting thousands of visitors a year in a trend known as “dark tourism.”

The World Trade Center memorial attracted 62,000 reviews on TripAdvisor in the year 2016 alone. 54% of those reviews rated the site where nearly 3,000 people died as “excellent.”

With its enduring reputation as a place of torture and death, the Tower of London was the second most reviewed site, followed by the Ann Frank House in Amsterdam; the location where the young Ann and her family hid from the Nazis in World War II. In Australia, the most reviewed dark tourism site was Port Arthur where Martin Bryant gunned down 35 people in1996.

Per the Palgrave Handbook of Prison Tourism, the term “dark tourism” was actually coined when people started visiting the scene of John F. Kennedy’s assassination in Dallas. In 2016, prison tourism was emerging as one of the most popular forms of tourism in the world.

You see it all the time. People lie on the steps in ruins, reenacting dead soldiers, or pose happily in front of the electric chair at the Texas Prison Museum. The truth is some people like the sinister and like the macabre. Some of these places are just so terrible the only way people can deal with them is to have a laugh. It can seem like we’re becoming more obsessed abut a quick personal experience in gathering places rather than understand the place.

There seems to be something about being close to the deep melancholy of a place that’s connected to tragedy. It arouses a sort of morbid thrill, a shiver of ghastliness. The same thing we might feel watching a horror film, only real. Just like the excited chatter that ensues after watching a terrifying movie, many travelers are keen to share their “haunted vacation stories on the web brimming with the same excitement.