At times, it seems that there is no single place on this planet, where the foot of man has never stepped. However, it is not true. There are quite a few places that remain a challenge for us. For example, while there's Mount Everest, world's highest mountain that was climbed by over 4,000 people, there are still numerous mountains in the world that weren't ascended even once. These mountains are usually called Virgin Peaks. Some of them are considered sacred and, for this reason, they are banned from climbing. Others are restricted due to political reasons. And there are also peaks that seem to be impossible to climb because of their dangerous terrain, harsh weather conditions, and remoteness of the area. Many climbers keep on dreaming to become the first to ascend one of these peaks, but as of today none of their attempts have been successful.

But it doesn't mean that if a mountain was climbed once, it becomes an easy task to ascend it for all climbers in the future. There are lots of peaks, where even experienced mountaineers, who seem to know what they are doing, encounter numerous problems to accomplish their goal and reach the summit. Weather changes rapidly there, avalanches are unpredictable, and there is always a risk of injury.

Right now, we are about to check out the toughest mountains in the world, climbed and unclimbed, that remain the dream for many seasoned alpinists. Some of them are feared, others are admired. And all of them arouse the adventurous spirit dormant in most of us.

20 Gangkhar Puensum, Bhutan (Virgin Peak)

Gangkhar Puensum, the supreme mountain in Bhutan, remains a Virgin Peak to these days and it's even considered the highest unclimbed mountain in the world (its elevation is 7,570 meters (24,840 feet) above sea level).

In the 1980s, when Bhutan opened its borders for mountaineering, several expeditions made attempts to climb this mount, but they were unsuccessful. Only one team was able to successfully reach the mountain's subsidiary peak in Tibet in 1998. The main peak of Gangkhar Puensum still remains unclimbed.

The people of Bhutan say that all attempts to ascend the mountain were unsuccessful, because it's inhabited by spirits and ghosts that keep people away from the summit. Who knows, perhaps they're right.

19 K2, China and Pakistan (Was Climbed)

Mount K2, aka Chhogori, is located in the Karakoram range. It's the second highest mountain in the world with an elevation of 8,611 meters (28,251 feet) above sea level. For the first time, this mountain was ascended back in 1954 (one year after the first successful ascent of Mount Everest), but it remains not nearly as popular as world's tallest mountain, not only because it's the second tallest, but also because only experienced climbers dare to ascend it.

Known as Savage Mountain among mountaineers, K2 is incredibly difficult in technical terms. Even the easiest route to the top requires crossing a glacier, ascending steep rocks, and finding a way through ice pillars that can collapse at any moment.

18 Muchu Chhish, Pakistan (Virgin Peak)

The elevation of Muchu Chhish, located in the Karakoram range, is 7,452 meters (24,591 feet). There were quite a few attempts to climb it, yet it still remains a Virgin Peak, because not only its summit is difficult to access, but also the mountain is located in the remote area.

There were only a few attempts to reach the summit. The most recent one took place in 2014, when English mountaineer Pete Thompson attempted to ascend the mountain with his team, but was forced to come back down at the 6,000 m (20,000 ft) point.

Unlike many other unclimbed mountains in the world, Muchu Chhish isn't considered to be a religious place and there're no political prohibitions to climb it, yet it remains a Virgin Peak to this day.

17 Mount Vinson, Antarctica (Was Climbed)

The elevation of Mount Vinson in Antarctica is 4,892 meters (16,050 feet). Being the highest point of Antarctica, this mountain is one the Seven Summits (a list of the highest mountains of each of the seven continents).

For the first time, Mount Vinson was climbed back in 1966. Since then, there were quite a few attempts to reach its summit, successful and not. Even though the elevation of this mountain isn't too high and technically it's not one of the most difficult mountains to climb, ascending it is still a task for experienced climbers. Mount Vinson is located in a remote area and weather on it can be extremely harsh, so even a minor accident on the ascent can quickly turn into a fatality.

16 Kailash, Tibet (Virgin Peak)

Mount Kailash is one of the most well-known unclimbed mountains in the world, surrounded by mystery, as well as by numerous legends. It's considered to be sacred by four religions: Buddhism, Hinduism, Jainism, and Bön. For this reason, in 2001 this mountain got banned from climbing.

But even before the ban, there were a few attempts to reach the summit of Kailash and all of them were unsuccessful. Although it's not as high as many other mountains that were ascended years ago (its elevation is 6,638 meters, or 21,778 feet), for some reason all attempts failed, often due to unexpectedly changing weather conditions. Or were the spirits guarding it and preventing mountaineers from getting to the top?

15 Annapurna, Nepal (Was Climbed)

Annapurna, located in the Himalayas in north-central Nepal, is considered one of the most dangerous mountains in the world. For the first time, it was climbed in 1950 and since then almost 200 people succeeded in their attempts to reach the summit.

With an elevation of 8,091 meters (26,545 feet) above sea level, Mount Annapurna has a very treacherous terrain and it is prone to heavy snows and avalanches. For example, in 2014, almost 2 meters (6 feet) of snow fell in 12 hours, which led to several avalanches. As a result, over 500 people needed rescue from the mountain. Unfortunately, 43 climbers didn't make it.

14 Kabru North Summit, India (Virgin Peak)

Kabru is a mountain in the Himalaya range located on the border of eastern Nepal and India. Its 7,412 meter (24,371 feet) summit, also known as Kabru North or Kabru IV, remains unclimbed to this day. The main reason why no one has ascended it yet is the treacherous terrain and propensity to avalanches.

Another reason of the failure to conquer Kabru North is the confusing topography of the region. In fact, Kabru is officially classified as a ridge, because it is home to multiple peaks. All of them ambiguously named and frequently confused to one another. So if you ever dare to climb any of Kabru's summits, be sure to know where you're going!

13 Nanga Parbat, Pakistan (Was Climbed)

Nanga Parbat is the ninth highest mountain in the world with an elevation of 8,126 meters (26,660 feet). Even though the name of this mountain is translated from Sanskrit as a "Naked Mountain", it's more known for mountaineers as a "Killer Mountain" or "Man Eater" due to the difficulties to climb it.

It's interesting that this mountain was the subject of German interest in the 1930s, because Everest could be accessed only by the British and Nanga Parbat seemed to be the highest reasonably scalable mountain at that time. But still, it wasn't an easy one to climb. For the first time, Nanga Parbat was ascended only in 1953 by Austrian climber Hermann Buhl, who finally succeeded after multiple failed attempts by other climbers.

12 Karjiang I, Tibet (Virgin Peak)

Karjiang is a mountain in Tibet, whose highest peak is elevated 7,221 meters (23,691 feet) above sea level, also called Karjiang I or Karjiang South, has never been climbed. The last serious attempt to ascend the mountain was undertaken in 2001 by a Dutch expedition. At some point of their journey, climbers had to come back, because the mountain looked very steep and too dangerous to climb, especially due to the weather conditions. The expedition decided to cancel the ascent to it. They only managed to climb nearby Karjiang III (with an elevation of 6,820 meters or 22,375 feet), before the team was forced to descend and then eventually depart altogether.

11 Denali, Alaska, USA (Was Climbed)

Denali, also known as Mount McKinley, is the highest mountain peak in North America. Its elevation is 6,190 meters (20,310 feet) above sea level. It's considered third most isolated peak on the planet and this is one of the reasons why it's difficult to climb it.

For the first time a group of people successfully ascended the mountain back in 1913. But even though this first successful attempt occurred much earlier than most others on this list, it doesn't make Denali any safer. In fact, the success rate of climbers on this mountain is only 50%. In other words, in yearly expeditions to the summit only half of climbers reach the top.

The main problem with Denali is its high altitude and extreme latitude, which means that altitude sickness is likely to kick in much faster than it does on other peaks.

10 Masherbrum, Pakistan (Virgin Peak)

Masherbrum, aka K1, is a mountain in the Karakoram mountain range in Pakistan. Since it was the first mapped peak in the Karakoram range, it's still known under the designation "K1" to many climbers.

The elevation of Masherbrum is 7,821 metres (25,659 feet) above sea level. Even though technically the summit of this mountain was reached in 1960 for the first time, you can see it on this list as a Virgin Peak, because its north face has never been climbed. The lack of successful attempts to ascend the north face of Masherbrum was due to a difficult route that only a very experienced climber might dare to take. Besides, it also requires your personal luck, because weather on the mountain changes very rapidly.

9 The Eiger, Switzerland (Was Climbed)

Located in the Bernese Alps of Switzerland, the Eiger was climbed for the first time a very long time ago. In 1858, Swiss guides Christian Almer and Peter Bohren and Irishman Charles Barrington ascended it from the South, and only in 1938 an Austrian-German expedition managed to climb the peak's more challenging north face. Ascending the north face is so difficult that this part of the mountain has even been nicknamed Mordwand, or Murder Wall.

Climbing the Eiger presents many technical difficulties, so it can be attempted only by experienced mountaineers. Heavy rockfall that may occur at any moment makes the chances even lower, so climbers have to rely not only on their experience, but also on their luck.

8 Labuche Kang III, Tibet (Virgin Peak)

On of the highest unclimbed mountains in the world and the highest non-prohibited unclimbed peak, Labuche Kang III in the Himalayas has an elevation of 7,367 meters (24,170 feet).

However, it's possible that Labuche Kang III will stop being a Virgin Peak very soon. This year, American climber Luke Smithwick is determined to get to its summit and go down in history of mountaineering. He wanted to gather a team to climb Labuche Kang III in spring of this year, but weather forecasts predicting harsh weather conditions prevented him from doing it. Now Smithwick plans to repeat his attempt this fall. Let's keep our fingers crossed for him!

7 Baintha Brakk, Pakistan (Was Climbed)

Baintha Brakk in the Karakoram mountain range was nicknamed the Ogre for a reason. It's considered to be one of the most difficult mountains to climb. Just think about it: the first successful attempt to reach its summit was back in 1977 and the second one - only in 2001, 24 years later!

Elevated by 7,285 meters (23,901 feet) above sea level, Baintha Brakk has an intricate shape, immense scale, and a harrowing incline. Mountaineers both fear and admire this mountain, but only the most hardcore enthusiasts and seasoned professionals dare to attempt to climb it. After all, any bold endeavor to ascend the Ogre is a real struggle.

6 Mount Siple, Antarctica (Virgin Peak)

Mount Siple isn't only a mountain. It's a potentially active Antarctic shield volcano. Due to its topography and remote location, Mount Siple receives very little publicity and there are no records about anyone successfully ascending it. Only a sketch map and very photos of it are available today. It means that before anyone decides to climb Mount Siple, it's required to do a profound research about it to eliminate possible risks.

In fact, we know only a few things about Mount Siple today. First, it's located off the coast of Marie Byrd Land on Siple Island. And second, it's elevated by 3,110 meters (10,200 feet) above sea level. Everything else is yet to become known.

5 Fitz Roy, Argentina (Was Climbed)

Fitz Roy is a mountain located in Patagonia, Argentina with an elevation of 3,405 meters (11,171 feet). For the first time, it was ascended in 1952 by French climbers. Even though a lot of time has passed since then, not too many successful attempts were made. On average, only one climbing team successfully reaches the summit of Fitz Roy per year. For this reason, it's still considered one of the most dangerous mountains to climb.

The danger of ascent is linked not to the height of the mountain. The thing is, its sheer granite surfaces and harsh weather conditions make the climbing process extremely difficult, even for experienced mountaineers.

4 Sauyr Zhotasy, China and Kazakhstan (Virgin Peak)

Sauyr Zhotasy is a mountain located on the border between Kazakhstan and China. It's the highest peak of the Saur Range, as well as of the entire Saur-Tarbagatai mountain range. Its elevation is 3,840 meters (12,600 feet) above sea level.

The mountain is located in a rather remote area and there are no records about attempts to climb it, which makes us think that no one has ascended it yet, at least officially. It's unclear what exactly makes Sauyr Zhotasy unclimbed, but we can assume that it's a combination of remoteness of the area, difficult weather conditions and, possibly, treacherous terrain. Probably, we won't learn until we go there and try!

3 Kangchenjunga, India and Nepal (Was Climbed)

Kangchenjunga is the third highest mountain in the world with an elevation of 8,586 meters (28,169 feet) above sea level. For the first time, it was climbed in 1955 and since then only 187 people successfully made it to the summit. The fatality rate of this mountain hasn't even decreased since the first ascent and it remains 22%.

It's interesting to note that none of the climbers, who ascended Kangchenjunga actually stepped on the summit. Since the mountain has a great religious significance among the Buddhists living in the region, first climbers made a promise that no one will stand on top of the mountain, so that it could remain intact. All climbers and climber teams that ascended Kangchenjunga afterwards followed the promise.

2 Kawagarbo, Meili Snow Mountains, Tibet (Virgin Peak)

Kawagarbo, the highest peak of Meili Snow Mountains, has an elevation of  6,740 meters (22,110 feet) above sea level. It's one of the most sacred mountains for Tibetan Buddhism and it's considered the abode of a warrior god of the same name. It attracts about 20,000 pilgrims every year, who worship and circumambulate the peak, making a long 240 km (150 mi) trek. Of course, out of respect to the mountain, none of the pilgrims even thinks of climbing it.

But climbers attempted to climb Kawagarbo numerous times, yet none of them succeeded. In 2001, the government banned climbing on the mountain due to its religious importance, so as of today Kawagarbo, as well as all other peaks of Meili Snow Mountains, remains intact.

1 Cerro Torre, Argentina and Chile (Was Climbed)

Cerro Torre, located in Southern Patagonia, not far from Fitz Roy, has an elevation of 3,128 meters (10,262 feet). It was climbed for the first time in 1974, yet it's still regarded as one of the hardest mountains to ascend. Those who want to reach the summit should be ready to deal with vertical and overhanging sections, as well as to tunnel through ice.

What makes the ascent even more difficult is the mushroom of rime ice that is often formed on Cerro Torre's top due to strong winds. If this ice cap is there, climbers evidently have no chance to get to the summit. Yet climbing to the top of Cerro Torre remains a dream for many mountaineers.

Do you feel the mountaineering spirit coming up in yourself?

References: World for TravelMatador Network, Atlas and Boots, Gear Junkie, Popular Mechanics