Some of the world's most celebrated landmarks nearly ceased to exist. Wars, natural disasters, political neglect, and the slow grind of time have all pushed these monuments to the edge of disappearance.
1. The Colosseum, Rome
Centuries of earthquakes left the Colosseum fractured, while stone robbers stripped its marble and travertine for reuse in other buildings across Rome. By the 1800s this amphitheater, once capable of holding 80,000 spectators, was a shadow of itself. Restoration campaigns in the 19th and 20th centuries halted further decay, and today ongoing work continues to stabilize its foundations and arches.
2. Angkor Wat, Cambodia
For centuries Angkor Wat lay partly hidden beneath dense jungle, battered by looting and the ravages of war. Decades of conflict, particularly during the Khmer Rouge regime, brought the site to the edge of ruin. After Cambodia's wars ended, international teams rushed to stabilize crumbling walls and restore its intricate carvings. Today it draws more than two million visitors a year.
3. Machu Picchu, Peru
Hidden for centuries in the Andes, Machu Picchu was thrust into international attention after its rediscovery in 1911. The influx of tourists and the constant threat of landslides placed the ancient Incan city at risk of irreversible damage. UNESCO and Peruvian authorities have since introduced strict visitor limits and ongoing stabilization of its most vulnerable structures.
4. The Leaning Tower of Pisa
For centuries, engineers feared the tower would topple entirely. The soil beneath it was too soft on one side, causing it to lean progressively more with each passing decade. A 20-year stabilization project completed in 2001 used a combination of soil extraction and counterweights to reduce the tilt by about 45 centimeters, enough to preserve the tower for at least another 300 years without erasing its famous lean.
5. Notre-Dame Cathedral, Paris
In April 2019 the world watched in real time as fire consumed the roof and spire of Notre-Dame, a cathedral that had stood at the heart of Paris since the 12th century. The blaze destroyed the 19th-century spire entirely and damaged significant sections of the vaulted ceiling. An unprecedented surge of international donations, eventually exceeding €800 million, funded a restoration effort that returned the cathedral to public use in December 2024.
6. Petra, Jordan
The rose-red rock-cut city of Petra, carved by the Nabataean kingdom more than 2,000 years ago, has faced relentless threats from earthquakes and natural erosion that have worn away its sandstone facades and intricate tombs. Tourism pressure has added to the strain. Conservation initiatives led by UNESCO and Jordanian experts are now stabilizing crucial sections of the Treasury and the surrounding canyon city.
7. The Alhambra, Granada
When Christian forces recaptured Granada in 1492, the Alhambra came within a hair's breadth of demolition. Napoleon's troops planted explosives in its towers in 1812 before a Spanish soldier cut the fuses at the last moment. The palace complex fell into severe disrepair throughout the following century before Washington Irving's famous 1832 book Tales of the Alhambra reignited international interest and helped set restoration in motion.
8. The Taj Mahal, India
The Taj Mahal has faced an unlikely enemy: air pollution. Decades of industrial emissions from nearby factories have slowly yellowed the white marble of Shah Jahan's 17th-century masterpiece. Authorities have imposed vehicle-free zones around the site, applied mud-pack cleaning treatments to the exterior, and relocated polluting industries. The tomb remains one of the most visited sites on earth, with over 7 million visitors annually.
9. Mont-Saint-Michel, France
The island abbey of Mont-Saint-Michel spent centuries as both a sacred pilgrimage site and a political prison. After the French Revolution, the monks were expelled and the complex converted into a jail that housed political prisoners for nearly 70 years, gradually falling into disrepair. Following its restoration as a religious monument, the causeway connecting it to the mainland was found to be silting up the surrounding bay. A major hydraulic engineering project completed in 2015 restored the island's natural tidal cycle.
10. The Dresden Frauenkirche, Germany
The Frauenkirche stood at the heart of Dresden for two centuries before Allied bombing in February 1945 reduced it to rubble. For decades the ruins were left as a war memorial in East Germany, a deliberate reminder of destruction. After reunification, an international campaign raised funds to rebuild it stone by stone, incorporating original blackened stones recovered from the debris. The restored church was reconsecrated in 2005.
11. Chichen Itza, Mexico
The Mayan city of Chichen Itza was largely swallowed by jungle for centuries after its abandonment. When 19th-century explorers began documenting the site, many structures were barely visible above the vegetation. Restoration work has been ongoing since the 1920s, though conservationists now face the challenge of managing millions of tourists whose physical contact with the stones is accelerating surface erosion.
12. The Easter Island Moai, Chile
The iconic stone figures of Easter Island, carved by the Rapa Nui people between roughly 1250 and 1500 AD, have faced centuries of toppling, looting, and erosion. Many were deliberately knocked over during internal conflicts on the island. International conservation efforts beginning in the 1990s have restored dozens of fallen moai to their upright positions, though rising sea levels and coastal erosion now pose a new and urgent threat.
13. The Parthenon, Athens
The Parthenon has survived fire, conversion into a church, a mosque, a gunpowder magazine, and a catastrophic explosion in 1687 when a Venetian mortar ignited Ottoman munitions stored inside. Its famous marble sculptures were removed by Lord Elgin in the early 1800s and taken to London, where they remain today at the center of an ongoing repatriation dispute. A restoration program that began in 1975 continues to this day.
14. The Great Wall of China
Stretching over 21,000 kilometers, the Great Wall has not aged evenly. Decades of agricultural activity, tourism pressure, and neglect have led to the collapse of roughly a third of its length. Sand dunes have buried sections in the Gobi Desert, and bricks have been removed by locals for construction material. A 2006 law made damaging the wall a criminal offense, and significant restoration work has stabilized the most visited sections near Beijing.
15. The Statue of Liberty, USA
By the early 1980s the Statue of Liberty was in serious structural trouble. Its original iron armature was corroding where it touched the copper skin, the torch was leaking water, and internal stairs had become dangerously unstable. A restoration that took four years and cost $87 million was completed in 1986, involving the complete replacement of the iron armature, a new torch, and a thorough inspection of the entire structure.
16. Palmyra, Syria
Palmyra had stood in the Syrian desert for two millennia before the Islamic State seized the city in 2015 and began systematically destroying its temples, triumphal arches, and funerary towers. The Temple of Bel and the Temple of Baalshamin, two of the most remarkable surviving examples of ancient Syrian architecture, were blown up. The city was recaptured in 2016, and international efforts to restore what remains are ongoing, though much is gone permanently.
17. The Palace of Westminster, London
The Palace of Westminster, home to the British Parliament, has been quietly deteriorating for decades. Surveys conducted in recent years have found crumbling stonework, failing drainage, corroded pipes, and asbestos throughout the building. Estimates for a full restoration have exceeded £13 billion. Without urgent intervention, engineers have warned that parts of the building could become unsafe within the next decade.
18. The Temple of Artemis at Ephesus
Once counted among the Seven Wonders of the Ancient World, the Temple of Artemis at Ephesus in modern-day Turkey was destroyed and rebuilt multiple times before being sacked by the Goths in 268 AD. Its final remnants were dismantled over subsequent centuries, with marble blocks repurposed for other buildings, including the Hagia Sophia in Constantinople. All that remains today is a single reconstructed column standing in an open field outside the town of Selçuk.
19. Chan Chan, Peru
The largest pre-Columbian city in South America, Chan Chan was the capital of the Chimú Empire and once housed over 100,000 people within walls of ornately carved adobe. Heavy rainfall from El Niño events has progressively dissolved its mud-brick structures, and poorly regulated tourism has accelerated the damage. UNESCO placed it on its list of World Heritage in Danger in 1986, and despite conservation efforts it remains one of the most threatened archaeological sites in the Americas.
20. The Arch of Ctesiphon, Iraq
The Taq Kasra, also known as the Arch of Ctesiphon, is the world's largest single-span brick vault still standing, built as part of the Sasanian royal palace near modern-day Baghdad around the 6th century AD. Flooding, erosion, and decades of conflict have left it dangerously unstable. Part of the structure collapsed in 1888 and again in 1909. International organizations have begun stabilization work in recent years, but the arch remains at serious risk of further collapse.
21. Ani, Turkey
Once the thriving capital of the medieval Armenian Bagratid kingdom with a population rivaling that of Constantinople, Ani was abandoned after Mongol and Timurid invasions and eventually forgotten beneath the windswept steppe near the Armenian border. Its cathedral, churches, and palace walls still stand, but have been deteriorating for centuries through neglect, looting, and lack of funding. UNESCO added it to its World Heritage list in 2016, finally bringing international attention to its precarious condition.
22. Leptis Magna, Libya
Leptis Magna was one of the most spectacular cities of the Roman Empire, birthplace of Emperor Septimius Severus and home to a monumental forum, a colonnaded street, a theater, and an arch that still stands remarkably intact. Since the 2011 Libyan civil war, the site has been largely unprotected from looting and damage, and it appeared on UNESCO's danger list as security in the region deteriorated. Some of the best-preserved Roman ruins in the world now sit largely unguarded in an unstable country.
23. Mohenjo-daro, Pakistan
One of the world's earliest and most sophisticated urban centers, Mohenjo-daro was built by the Indus Valley civilization around 2500 BC with planned streets, brick drainage systems, and multi-story buildings that were extraordinary for their time. Today its sun-dried mud bricks are slowly dissolving in the rain, and rising groundwater is pushing salts into the foundations. UNESCO and Pakistani authorities have warned that without urgent intervention, the site could be lost within decades.
24. Nan Madol, Micronesia
Called the Venice of the Pacific, Nan Madol is a series of artificial islands in the lagoon off the island of Pohnpei, built from massive basalt columns and coral blocks between roughly 1200 and 1500 AD. The site served as the ceremonial and political center of the Saudeleur dynasty and contains nearly 100 islets connected by canals. Today it is largely inaccessible and overgrown, its walls collapsing under the weight of vegetation. UNESCO placed it on its danger list in 2016 due to the absence of a management plan and active conservation.
25. Bagan, Myanmar
The plains of Bagan once held more than 10,000 Buddhist temples, pagodas, and monasteries built between the 9th and 13th centuries. A devastating earthquake in 2016 damaged hundreds of structures, and poorly managed restoration work using concrete and modern bricks nearly cost the site its UNESCO status. Political instability following the 2021 military coup has further hampered conservation efforts, leaving thousands of ancient monuments with inadequate protection and dwindling international support.
26. Persepolis, Iran
The ceremonial capital of the Achaemenid Persian Empire, Persepolis was built by Darius I around 518 BC and destroyed by Alexander the Great in 330 BC. What remained of its monumental staircases, columned halls, and intricately carved bas-reliefs has endured for over two millennia. Today the site faces threats from industrial pollution from nearby refineries, acid rain, and insufficient funding for conservation. Water infiltration and salt crystallization are slowly eroding the stone surfaces that carry some of the finest ancient reliefs ever created.
27. The Acropolis of Athens
Beyond the Parthenon, the entire Acropolis complex has faced extraordinary pressures over the centuries. The Erechtheion lost original Caryatid figures to pollution and to Lord Elgin, replaced today by replicas. The Propylaea was damaged by a 17th-century gunpowder explosion. A long-running restoration program has spent decades painstakingly disassembling, cataloguing, and rebuilding damaged sections using original marble wherever possible.
28. The Pyramids of Giza
The Pyramids of Giza have survived for over 4,500 years, but they have not done so untouched. Their original white Tura limestone casing stones were stripped over centuries for use in other buildings across Cairo, exposing the rougher core beneath. The Sphinx has required multiple restoration campaigns to halt erosion of its sandstone body. Today pollution, groundwater, and 14 million annual visitors continue to pose ongoing challenges.
29. The Tower of London
Built by William the Conqueror after 1066, the Tower of London has served as a palace, a prison, a treasury, an armory, and a zoo across its thousand-year history. By the 19th century it had fallen into serious structural decay, with crumbling walls and flooded foundations. A Victorian restoration campaign rebuilt significant sections, and today it is a UNESCO World Heritage Site, though conservationists continue to battle the effects of damp and stone erosion.
30. The Angkor Wat Tree Temples, Cambodia
Among the most visually dramatic of Angkor's threatened structures are the tree-engulfed temples, where enormous silk-cotton and strangler fig trees have grown directly into walls and doorways over centuries. At Ta Prohm, the trees and stonework have become so intertwined that removing one risks destroying the other. Conservationists face the extraordinary challenge of preserving both the ruins and the living organisms growing through them, in a balance that has no easy answer.
