Exploring former concentration camps, radiation zones or bombing sites certainly isn't for everyone but millions of travelers flock to these dark destinations each year to pay their respects to the victims, satisfy their curiosity and conquer their fear. Travel website My Late Deals has rounded up some of the most popular dark tourism sites from around the globe. Here are eight guaranteed to leave you in awe.

Open daily and free to visit, New York City's National September 11 Memorial is located on the former site of the Twin Towers at the World Trade Center, where more than 2,600 people perished during the 9/11 terrorist attacks in 2001. Museum tickets can be purchased online up to six months in advance and include access to every exhibition.

The Auschwitz-Birkenau Memorial and Museum at the site of the former German Nazi Concentration and Extermination Camp is located about an hour west of Krakow, Poland. Auschwitz was the largest of the German Nazi concentration camps. More than 1.1 million men, women and children died here during World War II.

Hiroshima was the first city to be attacked with an atomic bomb in August 1945. Today, the Hiroshima Peace Memorial Museum stands in honor of the victims and as a reminder of the devastating effects of nuclear weapons. The museum is open year-round and only costs 200 yen or a couple of American dollars to explore.

The recent HBO miniseries about the infamous Chernobyl nuclear disaster near Pripyat, Ukraine has tourists buzzing. More than 30 years after the explosion at the No. 4 nuclear reactor in the Chernobyl Nuclear Power Plant, local tour companies are experiencing high demand from visitors who want to see the abandoned site for themselves.

An overwhelming experience for many, the Murambi Genocide Memorial in southern Rwanda preserves the site of an unthinkable massacre during the 1994 Rwandan genocide. Victims here numbered in the tens of thousands. Hundreds of the bodies have been exhumed and mummified to appear as they did when Hutu Interahamwe militiamen attacked more than two decades ago.

Visitors to San Francisco can explore Alcatraz Island and the notorious former maximum-security federal prison with Alcatraz Cruises. Alcatraz housed some of the most high-profile criminals throughout American history, including Al Capone and George "Machine Gun" Kelly.

Located near modern-day Naples, Italy, the ancient Roman city of Pompeii was wiped out in AD 79 with the violent eruption of Mount Vesuvius. Several feet of volcanic ash preserved much of Pompeii. Today, tourists flock to the expansive site to experience a unique time in Roman life.

The Killing Fields of Choeung Ek is located about 10 miles south of Phnom Penh, Cambodia and mark a site where the Khmer Rouge regime executed shocking numbers of men, women and children in the late 1970s. The Killing Fields are open daily and admission costs only $6 and includes an audio tour.