While we hope the world’s most important landmarks will remain for future generations to see firsthand, the sad fact is that many have already been destroyed, and countless others are at risk. Here’s a look at seven landmarks to visit before they’re gone forever.

White Cliffs of Dover in England

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Researchers have found that England’s famous White Cliffs of Dover have been eroding ten times faster during the last 150 years versus the 7,000 years before. In the past, the wide beaches in the area helped slow erosion of the iconic white cliffs. However, very little beach remains, accelerating the rate of erosion.

Queen’s Head Rock in Taiwan

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Visit Taiwan, where you’ll find Yehliu Geopark, home to fascinating rock formations. One of these is the iconic “Queen’s Head,” given the name due to its supposed resemblance to Queen Elizabeth I. However, erosion is threatening to behead the queen, who already has a crack at the base. Researchers are worried that the head could break off in the next five to ten years if something isn’t done. Yehliu has now placed guards around the rock to ensure no sabotage, and there are plans to reinforce the rock and continue monitoring erosion.

Stonehenge in England

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Stonehenge’s importance extends beyond the mysterious standing stones that are recognizable around the world. It is part of a larger World Heritage area with unexplored burial grounds, ancient settlements and potentially the key to unlocking the mystery as to why Stonehenge was built. Archaeologists are at war with the British Government, which plans to build a tunnel underneath the site, a move that threatens to potentially destroy important artifacts. Some critics are also extremely concerned that a tunnel could destabilize the neighboring ground and cause the stones to sink, shift or even fall over.

12 Apostles in Australia

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The 12 Apostles along the Great Ocean Road is one of Australia’s most popular destinations, named for the dramatic limestone stacks seen along the coast. Despite the name, there are not 12 apostles visible. There were originally nine limestone stacks when Victoria Tourism christened them in the 1920s, and now there are only eight after erosion caused one to collapse. With continued erosion, experts estimate more limestone stacks are at risk of disappearing.

Mendenhall Glacier in Alaska

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Unfortunately, the risk of disappearing is a reality for countless glaciers around the world. Juneau’s famed Mendenhall Glacier is melting at a rapid pace — over 9,000 feet in 100 years. Cameras were installed in 2007 and show that Mendenhall Glacier has retreated more than 1,830 feet — about one-third of a mile — in just eight years.

Petra in Jordan

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Petra is famous for sandstone buildings, like the iconic Al-Khazneh (The Treasury), that date back to the first century B.C. However, increased tourism and erosion are two factors taking their toll on the ancient site. Erosion has increased due to wind and rain, while site-management issues and structural instability also threaten Petra’s future. However, one of the biggest risks to Petra is the people who visit the site. Tourists leaning on or touching The Treasury have caused the surface to erode by 1.5 inches in only 10 years.

The Dead Sea

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The shores of the Dead Sea are changing rather dramatically as it continues to shrink at a rather alarming rate. Experts estimate it could become a tiny pool by the middle of this century. On average, the sea levels are falling by as much as five feet per year. Some resorts and spas have been forced to close, while others that were once beachfront properties are taking visitors down to the shore by tractor train.