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Kawah Ijen volcano, Indonesia -

One of the few places on Earth where you can witness blue fire ignited by sulfur, the Kawah Ijen volcano in East Java really does resemble the devil's playground. A crater lake of sulfuric acid belches out gas like a demon's breath, while the surrounding landscape is seared with heat that can reach up to 600°C (1,112°F).

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Prypiat, Ukraine -

A tragedy of truly frightening dimensions, the Chernobyl disaster of April 1986 prompted the total evacuation of Prypiat, the city nearest the stricken nuclear power plant. Today it's a contaminated ghost town, a ghastly reminder of one of the scariest episodes in modern history.

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The Gates of Hell, Turkmenistan -

The Darvaza gas crater in the middle of the Karakum Desert in Turkmenistan is a burning natural gas field that's been imaginatively described as the "Gates of Hell." It really does conjure up an image of a satanic sinkhole where mortals are swallowed up by a devilish inferno.

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The Beelitz-Heilstätten hospital, Germany -

Built in 1898, the Beelitz-Heilstätten hospital served as a sanatorium for lung diseases. During the First World War, a young Adolf Hitler was treated here, temporarily blinded by a British gas attack and wounded in the leg at the Battle of the Somme. After 1945, the Soviets used the complex as a military hospital. Mostly abandoned in 1990, its spooky interior makes  for uncomfortable exploration.

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Capuchin Catacombs, Italy -

Dating back to the 16th century, the Capuchin Catacombs in Palermo, Sicily, welcome the curious with about 8,000 corpses and 1,252 mummies, many in a remarkable state of preservation.

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The Road of Death, Bolivia -

Otherwise known as the Yungas Road, this used to be one of the most dangerous highways in the world: by the mid-1990s, an average of 300 drivers per year were falling victim to its perilous conditions. Now closed to vehicle traffic, the "Road of Death" is today only followed by cyclists and hikers, who still take enormous risks by doing so.

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Aokigahara Forest, Japan -

Aokigahara Forest, also known as the Sea of Trees, textures the northwestern flank of Mount Fuji on the island of Honshu in Japan. Its poetic sobriquet, however, belies a sinister secret. It's here under a dark canopy that dozens of unfortunate souls have opted to take their own lives. This grim fact plays into the forest's historical reputation as a home to yūrei: ghosts of the dead in Japanese mythology.

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Centralia, USA -

Centralia is a modern-day ghost town. Just five people remain in this Pennsylvania community after a coal mine fire began burning beneath the borough in 1962. Intense heat cracked open highways like eggshells, while toxic gases have made the place almost uninhabitable. Almost.

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Auschwitz concentration camp, Poland -

Its very name conjures up images of unimaginable horror and suffering. Indeed, Auschwitz remains one of the world's most infamous destinations. Even those with iron constitutions can't help but shudder at the thought of what took place here.

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Cahills Crossing, Australia -

Traversing Cahills Crossing in Australia's Northern Territory is a rite of passage for many adventure tourists. But if the floodwaters don't kill you, the crocodiles that hang out either side of what's been described as one of the world's most dangerous bridges possibly will. Can you spot the croc in this photo, waiting for an easy lunch?

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Lake Natron, Tanzania -

Lake Natron in Tanzania is so caustic that it appears as liquid rust when viewed from the air. The alkalinity of the lake can reach a pH of greater than 12, with the water temperature on occasion reaching a scalding 60°C (140°F). Not a place to take a dip.

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Queimada Grande Island, Brazil -

Queimada Grande Island, commonly referred to as "Snake Island," lies anchored off the coast of Brazil. Residents include the highly venomous golden lancehead (pictured), a creature categorized on the International Union for Conservation of Nature (IUCN) Red List as Critically Endangered. Due to the proliferation of serpents, the destination is closed to the public.

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The Hill of Crosses, Lithuania -

While the Hill of Crosses serves as a major site of Catholic pilgrimage, this collection of an estimated 10,000 crosses, crucifixes, and statues of the Virgin Mary embroidering land near the city of Šiauliai can still startle the uninitiated.

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Nagoro Doll Village, Japan -

Set in the Iya Valley on the island of Shikoku in Tokushima Prefecture, Nagoro presents the visitor with a truly unnerving sight. Dozens of realistic life-sized dolls are positioned around the village, silent but all seeing.

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Death Valley, USA -

The highest temperature reliably recorded on Earth was a blistering 56°C (134°F) in Death Valley in 1913. But the way things are going, that record may well be shattered, and sooner rather than later. Meanwhile, getting stranded in a place like this is a truly terrifying thought.

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Blood Falls, Antarctica -

The Taylor Glacier in Antarctica's Victoria Land region features a weird geological phenomenon: it bleeds! Actually, the so-called Blood Falls is an escaping flow of iron oxide-rich ancient ocean water trapped under the glacier that seeps into McMurdo Sound.

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Island of Dolls, Mexico -

Children's doll, hundreds of them, appear as grotesque mannequins scattered throughout island forests of Xochimilco near Mexico City. The unwholesome installation is said to have been inspired after the body of a young child was discovered in one of the channels.

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Sedlec Ossuary, Czech Republic -

Located in a chapel in the former Sedlec Abbey in Kutná Hora, this morbid ossuary is estimated to contain the skeletons of between 40,000 and 70,000 people.

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Gomantong Caves, Malaysia -

This intricate cave system in Sabah can appear intimidating, indeed. And if bats give you the jitters, stay out! Otherwise, the more adventurous can marvel at the sheer scale of this gargantuan limestone cathedral and its colony of wrinkle-lipped free-tailed bats.

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Parikkala Sculpture Park, Finland -

It's not often that a work of art sends shivers down your spine, but in the Finnish town of Parikalla there's a park inhabited by a collection of strange-looking sculptures whose odd demeanor can catch you unaware.

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Bhangarh Fort, India -

Bhangarh is not for the nervous. This 16th-century fort built in Rajasthan is said to be haunted, cursed by a priest who was a practitioner of black magic.

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Winchester Mystery House, USA -

Not for nothing is this California mansion so named. The Winchester Mystery House in San Jose defies logic for its architectural curiosities, features such as staircases that lead nowhere and doors that open to walls. And somewhere in this building is a ghost waiting to haunt the unwary...

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Christ of the Abyss, Italy -

More unusual than terrifying, the Christ of the Abyss is a submerged bronze statue found offering a benediction of peace on the spot where a scuba diver perished in the 1940s. It stands, clad in barnacles, on the seabed off San Fruttuoso on the Italian Riviera.

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Catacombs of Paris, France -

Incredibly, the network of underground ossuaries hidden under the French capital hold the remains of millions. Delve into the belly of the dead if you dare...

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Glencoe, Scotland -

Even on a bright sunny day, Glencoe gives you the creeps. On February 13, 1692, 30 members of the Clan MacDonald were massacred in these hills, victims of Scottish government forces. It's said that on certain days in winter the remote and empty landscape is filled with the cries of the dying.

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Gettysburg Battlefield, USA -

According the American Battlefield Trust, as many as 7,000 combatants from both sides fell at Gettysburg, with thousands more wounded or taken prisoner. One of the most hallowed sites of the American Civil War, Gettysburg is said by many to be haunted by the spirits of young soldiers tormented by their early demise.

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Blue Hole, Egypt -

Only the bravest and most experienced scuba divers take the plunge and explore the Blue Hole. This 120-m (393 ft) submarine sinkhole on the coast of the Red Sea is ominously known as the "diver's cemetery" for the estimated 200 fatalities a year recorded by authorities. Its notoriety has lent it the nickname "Black Hole."

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Craco, Italy -

As ghost towns go, Craco, in the southern Italian region of Basilicata, at least imparts a certain aesthetic appeal. But beware! Apart from the real threat of landslides, this place is reputed to be haunted by the spirits of past disgruntled residents, who were forced to relocate after their properties were condemned as being unsafe.

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Danakil Depression, Eritrea -

The one place on Earth hot enough to give Death valley a run for its money, the Danakil Depression on the Horn of Africa is, however, far more menacing for its hostile, sulfur-laced environment.

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Eastern State Penitentiary, USA -

Spooky hardly describes the atmosphere pervading the Eastern State Penitentiary, a former corrections facility in Philadelphia. This was the world's first penitentiary, opened in 1829. Notorious inmates included mobster Al Capone and the infamous but highly successful bank robber "Slick Willie" Sutton.

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Hanging Coffins, Philippines -

The locals of Sagada, a mountain town in the Philippines, still follow a tradition of "burying" their dead by depositing the deceased in coffins that are suspended from a nearby cliff face.

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Mud volcanoes, Azerbaijan -

Azerbaijan's Gobustan State Historical and Cultural Reserve burps, belches, and brings up mud from deep within hundred of volcanoes to lend the region a truly unworldly appearance. The park is also known for its ancient rock art.

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Wittenoom, Australia -

Wittenoom in Western Australia has the dubious honor of being the "largest contaminated site in the southern hemisphere." Blue asbestos was once mined here long before anybody was aware of its harmful properties. Today only fools venture beyond the warning signs without taking precautions.

Sources: (CNN) (IUCN) (American Battlefield Trust) (The Guardian)

See also: Things you might not realize are hurting your lungs

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