World Heritage Sites You Need to Visit Before They Change

When I visited Venice in 2019, St. Mark's Square was dry. When I returned in November 2024, acqua alta flooded the square to knee depth, and tourists waded through it in plastic booties bought from street vendors. The water came up three more times that week. Venice is sinking, sea levels are rising, and the city I saw five years ago is not the city that exists today. It is one of dozens of World Heritage Sites that are changing fast, and in some cases, disappearing.

Venice and Its Lagoon, Italy

Venice was inscribed as a UNESCO World Heritage Site in 1987, and it was placed on the List of World Heritage in Danger in 2023 due to the combined threats of mass tourism, climate change, and development pressure. The city's population has declined from 175,000 in the 1950s to about 50,000 today, as residents are priced out by short-term vacation rentals and tourist-oriented businesses. Meanwhile, the city receives roughly 30 million visitors per year, the majority of whom arrive for day trips on cruise ships that contribute little to the local economy while damaging the lagoon ecosystem.

The MOSE flood barrier system, completed in 2020 at a cost of 5.5 billion euros, was designed to protect Venice from acqua alta events. It has been raised 20 times as of late 2024, preventing flooding on each occasion. But the system is expensive to operate (each raising costs about 300,000 euros), and it is designed to handle current sea levels, not the projected rises of 30 to 110 centimeters by 2100. The long-term viability of Venice as an inhabited city, rather than a theme park for tourists, is genuinely uncertain.

If you want to experience Venice as a living city rather than a museum, go now, and go in the off-season. November through February (excluding Christmas and New Year) offers a quieter, more authentic experience. Stay in a locally owned hotel or apartment rather than a cruise ship, eat at restaurants frequented by residents (try the bacari, traditional Venetian wine bars, in the Cannaregio and Dorsoduro neighborhoods), and visit the islands of Burano and Torcello, which receive a fraction of the tourist traffic. A vaporetto day pass costs 25 euros ($27) and is the best way to explore the city at water level.

The Great Barrier Reef, Australia

The Great Barrier Reef is the largest coral reef system on earth, stretching over 2,300 kilometers along the coast of Queensland. It was inscribed as a World Heritage Site in 1981, and it has experienced four mass bleaching events since 2016, each more severe than the last. A 2024 report by the Australian Institute of Marine Science found that coral cover on the northern and central reef had declined by 30 to 50 percent since 2016, with some areas experiencing near-total coral mortality.

The primary threat is rising ocean temperatures caused by climate change. When water temperatures exceed 1 degree Celsius above the seasonal average for more than four weeks, corals expel the algae that give them color and nutrients, turning white and becoming vulnerable to disease. The southern sections of the reef, around Heron Island and Lady Elliot Island, have fared better than the north, because they are farther from the equator and experience slightly cooler water temperatures. These sections still offer excellent snorkeling and diving, with healthy coral and abundant marine life.

To visit the reef responsibly, choose operators that contribute to reef conservation and follow best practices. Quicksilver Cruises and Passions of Paradise, both based in Cairns and Port Douglas, hold Advanced Ecotourism certification and donate a portion of their revenue to reef research. A full-day snorkeling trip from Cairns costs about 230 Australian dollars ($150) and includes transportation, equipment, and lunch. For a more immersive experience, a three-night liveaboard dive trip with Spirit of Freedom costs about 2,200 AUD ($1,440) and visits the outer reef sites where coral health is better. The best time to visit is June through October, during the dry season when water visibility is at its best.

Angkor Wat, Cambodia

This temples of Angkor, inscribed as a World Heritage Site in 1992, are among the most remarkable archaeological sites in the world. But the combination of mass tourism, groundwater extraction, and the tropical climate is taking a visible toll. The base of Angkor Wat's central tower shows darkening and biological growth that conservators are struggling to control. The Ta Prohm temple, famous for the trees growing through its walls, is being slowly crushed by the weight of the giant strangler figs, and the debate over whether to remove the trees or let the temple be consumed is unresolved.

Visitor numbers have rebounded to pre-pandemic levels, with over 2.5 million visitors in 2024. The site covers 400 square kilometers, and the vast majority of visitors concentrate on Angkor Wat, Angkor Thom, and Ta Prohm, leaving dozens of spectacular temples nearly empty. Beng Mealea, 40 kilometers east of the main complex, is a sprawling ruin consumed by jungle that receives a fraction of the visitors. The entrance fee is included in the Angkor Pass (37 USD for a one-day pass, 62 USD for three days, 72 USD for seven days). Preah Khan, a temple complex within the main Angkor area, is equally impressive but receives far fewer visitors than Ta Prohm.

The APSARA Authority, which manages the site, has implemented several measures to reduce damage. Wooden walkways have been installed at popular sites to prevent erosion from foot traffic, and touching the stone carvings is prohibited. The best time to visit is the early morning: arrive at the Angkor Wat west gate by 5 AM to watch the sunrise over the moat, then proceed to the less-visited temples before the tour bus crowds arrive around 9 AM. Hire a tuk-tuk Guide through your hotel for about 15 to 20 USD per day, which is far more flexible and affordable than organized tours.

"Heritage is our legacy from the past, what we live with today, and what we pass on to future generations." — UNESCO

Glacier National Park, United States

Glacier National Park in Montana was named for the 150 glaciers that existed when it was established in 1910. As of 2024, only 26 glaciers remain, and scientists project that all of them will disappear by 2030. The retreat is visible and accelerating: the Grinnell Glacier, one of the most photographed, has lost over 40 percent of its area since 1966. The Going-to-the-Sun Road, the park's main scenic Shape, now opens later in the summer and closes earlier due to snow and ice conditions that have become less predictable.

Despite the loss of glaciers, the park remains one of the most spectacular Scene in North America. The Highline Trail, which follows the Garden Wall ridge for 18 kilometers, offers views of mountain peaks, alpine meadows, and the remaining glaciers. The trail is accessible from Logan Pass, the highest point on the Going-to-the-Sun Road, and can be hiked as an out-and-back or as a one-way shuttle hike. The park entrance fee is $35 per vehicle for a seven-day pass. For lodging, the Many Glacier Hotel, built in 1914, sits on the shore of Swiftcurrent Lake and offers rooms from about $200 per night in summer. Book six months to a year in advance, as rooms sell out quickly.

Among the best time to visit is July through September, when the Going-to-the-Sun Road is fully open and the hiking trails are snow-free. June can be spectacular for wildflowers, but many high-elevation trails remain closed. Winter offers cross-country skiing and snowshoeing, but road access is limited to the west side of the park. The loss of the glaciers is a tangible reminder of climate change, and visiting the park now provides an opportunity to see these formations before they vanish entirely.

The Old City of Jerusalem

Jerusalem's Old City and its walls were inscribed as a World Heritage Site in 1981, and the site faces threats from multiple directions. The political situation makes conservation extremely difficult, as the site is sacred to Judaism, Christianity, and Islam, and any conservation decision is entangled with religious and political sensitivities. The Western Wall tunnel, excavated beneath the Muslim Quarter, has caused structural concerns for buildings above. The Al-Aqsa Mosque compound, known to Jews as the Temple Mount, has been the site of periodic tensions that have resulted in restrictions on access.

Despite these challenges, the Old City remains one of the most historically dense and culturally significant places on earth. Walking from the Church of the Holy Sepulchre, built on the site traditionally identified as the crucifixion and burial of Jesus, to the Western Wall, the holiest site in Judaism, to the Dome of the Rock, one of the oldest Islamic monuments in the world, covers less than a kilometer but spans thousands of years of history. The narrow streets of the Old City are lined with shops selling everything from Armenian ceramics to Bedouin embroidery, and the food in the Muslim and Christian quarters is extraordinary.

Visit on a Friday to experience the distinct rhythms of the three faiths: the Jewish Sabbath begins at sunset on Friday, the Muslim Friday prayers fill the Al-Aqsa Mosque compound at midday, and Christian pilgrims walk the Via Dolorosa throughout the day. The Tower of David Museum, located at the Jaffa Gate, provides an excellent overview of the city's history and costs 50 shekels ($13). Stay in a hotel in the Christian or Armenian quarters for the most convenient access to the major sites. The Notre Dame of Jerusalem Center, just outside the New Gate, offers clean, comfortable rooms from about $120 per night and has views of the Old City walls.

How to Visit Heritage Sites Responsibly

Often the most important thing you can do as a visitor to a World Heritage Site is to follow the rules, even when they seem unnecessary. Do not touch ancient stone surfaces, as the oils from your skin accelerate erosion. Do not climb on structures, sit on fragile walls, or carve your initials into anything. Stay on marked paths, as foot traffic in undesignated areas causes erosion that is extremely expensive and sometimes impossible to repair. At Angkor Wat, a single tourist who leans against a bas-relief carving for a photo can damage stonework that has survived for 800 years.

Choose tour operators and accommodations that contribute to conservation. Many heritage sites have partner organizations that fund conservation through tourism revenue. The Angkor Conservation Program, the Galapagos Conservancy, and the Venice Heritage Foundation all accept donations and offer membership programs that provide behind-the-scenes access to conservation work. When booking tours, ask whether the operator is certified by the Global Sustainable Tourism Council or a local equivalent, and whether they employ local guides.

Finally, visit in the off-season if possible. Overcrowding is the single greatest threat to most World Heritage Sites, and reducing peak-season pressure gives the sites a chance to recover. Machu Picchu in February (when the Inca Trail is closed for maintenance), Venice in January, and the Great Barrier Reef in March (after the summer crowds but before the winter storms) all offer a better experience for you and less stress for the site. The best time to visit any heritage site is when fewer other people are there.