Intrepid travelers have a tendency to gravitate toward heights. Mountaintops, skyscrapers, Ferris wheels — the higher the better. But traveling in the opposite direction, below the ground, can provide a whole new level of excitement. The following tunnels, mines, and even entire subterranean cities are hidden within the depths of the Earth, waiting to be explored. Read below (pun intended) for seven of the world’s most incredible underground landmarks.

Wieliczka Salt Mine – Poland

Descending 1,000 feet below ground, Poland’s Wieliczka Salt Mine dates back to medieval times. Named one of the original 12 UNESCO World Heritage Sites in 1978, the massive salt mine features a tiered underground network of tunnels and connecting rooms. It was operational from the 13th century, when salt was a highly valued commodity due to its ability to preserve food, all the way through the late 20th century. 

During the height of salt mining, Wieliczka expanded into nine levels to accommodate the area’s Catholic miners who lived underground seasonally. As a result, subterranean salt chapels were installed so these devout workers could still practice their faith. Perhaps the most impressive of these is St. Kinga’s Chapel, located 330 feet underground and featuring a giant salt chandelier and elaborate salt sculptures. Today, visitors can not only tour the inoperative salt mine’s extensive tunnels and chapels but also attend mass on Sundays.

Kaymakli Underground City – Turkey

Situated in central Turkey almost 300 feet beneath the town of Cappadocia, Kaymakli Underground City was built in seventh century BCE for Christians to hide from persecution during the reign of the Ottoman Empire. To accommodate the needs of its residents in hiding, the Christian refugees created a complex organized community — entirely underground.

With space for up to 3,000 people, Kaymakli consisted of small rooms for citizens to sleep in, with storage spaces, water wells, and ventilation shafts added to make underground life more comfortable. The city also contained burial chambers, a kitchen, and a church for Christian worship. Of the Kaymakli’s eight floors, only four remain accessible to visitors today, who will need to navigate steep stairways and narrow passageways throughout the tour.

Dambulla Cave Temple – Sri Lanka

As one of the largest and best-preserved cave temples in the world, Dambulla Cave Temple is an active Buddhist shrine dating back 2,000 years. The religious complex actually contains five cave temples, the first of which was carved into the rock by Buddhist monks sometime between the first and third centuries BCE. Over time, ancient kings funded four other cave temples to be built as a gesture of gratitude to the Buddha.

Inside the temples, 157 statues are on display — including a 45-foot-long reclined Buddha — while intricate cave murals depict the life and teachings of Siddhartha. As a sacred pilgrimage and a place of worship, the cave temples are open to the public with certain stipulations. A strict dress code forbids shoes and hats and requires knees and shoulders to be covered.

Blair Street Underground Vaults – Edinburgh, Scotland

This unique site in Edinburgh’s Old Town sprang up in 1788 after the city’s South Bridge was completed. The bridge’s lower levels, home to numerous arched vaults and chambers, quickly transformed into a busy subterranean community beneath the streets of the Scottish capital. 

At first, cobblers, metalsmiths, and merchants gathered in the Blair Street Underground Vaults to hawk their wares, but due to flooding and lack of ventilation, these businesses eventually departed for higher ground. Brothels, gambling rings, and unlicensed distilleries replaced them, and the vaults became synonymous with unseemly business and criminal activity. After being sealed off in the mid-1800s, the vaults were rediscovered in the 1980s. Today, the underground site is rumored to be haunted — in addition to daytime tours, night tours are available for the very brave.

City Hall Subway Station – New York, New York

Located directly beneath New York City Hall, this long-forgotten subway station has been abandoned for over half a century. Designed by Heins & LaFarge, the same firm behind the Bronx Zoo, the City Hall Subway Station is an architectural marvel featuring vaulted tiled ceilings and leaded glass skylights. With hopes that a rapid public transit system would transform New York into a world-class metropolis, officials unveiled the City Hall Station on October 27, 1904 — the same day the New York City Subway opened to the public. 

As train technology advanced, the city abandoned the station in 1945, since the newest models of trains could not navigate the station’s sharpest curve. Today, tours of the old subway station can be made through the New York City Transit Museum, but word of caution: tickets tend to sell out well in advance.

Catacombs of Paris – France

With the bones of approximately 6 million bodies hidden beneath the city’s 14th, 15th, and 16th arrondissements, the Paris Catacombs are one of the most fascinating sites in the city. The reasoning behind the mass grave is a practical one: In 1785, due to a surplus of bodies in the communal cemeteries, the government began transferring bones to a network of underground mines 65 feet beneath the city.

Once in the catacombs, the bones of the dearly departed were shaped into meticulous and macabre designs, even forming tunnels and archways. In 1809, the city opened the catacombs to visitors, and it has since become one of Paris’ most popular historic sites. Although the network of tunnels runs for 124 miles, less than two miles remain open for public exploration.

Churchill War Rooms – London, England

Beneath the streets of Westminster, the Churchill War Rooms is where the famous prime minister slept, strategized, and schemed ways to defeat the German troops during World War II. Here, stationed inside these top-secret subterranean rooms, the British government fought the tactical side of war. The map room — untouched since 1945 — is notably where Churchill, King George VI, and other leaders convened to discuss the progress of the Allied Forces.

The rest of the mesmerizing underground displays are also frozen in time, including the bunkers where British citizens hid during the Blitz and the cabinet room where crucial decisions were made. Both guided and self-guided tours are available of the Churchill War Rooms and the adjoining Churchill Museum.

Though they have plenty of imitators, some landmarks stand in a category of their own. There’s only one true Eiffel Tower (sorry, Paris, Tennessee — yours doesn’t count), one Stonehenge (although Nebraska’s take, called Carhenge, is worth checking out), and one Great Pyramid (nice try, Memphis). But maybe you’ve already visited these legendary landmarks or are just interested in a less stressful, less crowded experience. Luckily, there are many appealing alternatives out there. Here are five of our favorite attractions which — while a little less famous than their counterparts — are well worth visiting in their own right.

Choquequirao – Peru 

Move over, Machu Picchu: The Incan ruins at this site high in the Andes mountains are three times larger than those at its much more famous cousin. Yes, Choquequirao — located around 30 miles away from Machu Picchu — is more difficult to access. But although the trek is longer and more physically demanding, Choquequirao (with a name meaning “Cradle of Gold”) receives fewer than 10,000 visitors a year. In contrast, Machu Picchu sees more than 1.5 million. 

Archaeologists only began excavating Choquequirao in the 1970s, and so far, only about a third of the site has been exposed. A long-promised cable car will eventually make Choquequirao more accessible and drastically increase the number of tourists — so channel your inner Indiana Jones and see it while it’s still untouched.

Herculaneum – Italy

Like Pompeii, this ancient Roman town near modern-day Naples is located in the Campania region of Italy and was likewise decimated by the catastrophic volcanic eruption of Mount Vesuvius in 79 CE. Although both cities were destroyed, working-class Pompeii was blanketed in a relatively soft and shallow layer of ash and pumice, whereas the wealthy seaside resort of Herculaneum was preserved under 65 feet. This included a hard top layer that kept oxygen out, preserving wooden staircases, doors, and other organic materials. Pompeii’s earlier excavation led to its greater fame — and today is visited by around 3 million tourists a year. Modest Herculaneum, on the other hand, sees a mere 300,000 visitors on average.

Frenchmen Street – New Orleans, Louisiana

Anyone who’s ever heard of New Orleans is probably familiar with Bourbon Street. The street in the city’s French Quarter is rightly famous for its party atmosphere (particularly during Mardi Gras), restaurants and music venues, and historic architecture with wrought iron balconies. But locals and in-the-know visitors avoid the often out-of-control revelers on the city’s most famous street and head to Frenchmen Street instead. Once a hidden gem known mostly to residents, this street in the Seventh Ward has a short stretch in the Faubourg Marigny neighborhood offering some of the best music New Orleans has to offer. At the southern end of Frenchmen Street, you’ll find the New Orleans Jazz Musuem.

Bruges – Belgium

If you’re looking for charming canals and medieval architecture with fewer crowds, this city in northwest Belgium is the place for you. No, it’s not Venice — nor does it need to be. Swans float on peaceful waterways, while sunny flower-bedecked squares sport grand churches, major museums, and restaurants offering the city’s famed chocolates, frites, and Belgian beers. If you still have your heart set on Venice, we recommend at least checking out some of the less popular spots nearby: Take the ferry to Chioggia, an authentic (and canal-crossed) Italian fishing village only 15 miles from the city.

Edge – New York, New York

If you’ve admired the city’s iconic skyline from atop the Empire State Building or sipped a sunset martini from the late, great bar at 30 Rock’s Rainbow Room, you’ve definitely experienced classic New York City views. For something completely different but no less breathtaking, head west to Hudson Yards, a more recent addition to Manhattan’s melting pot of neighborhoods. The high-end 28-acre development — located between Hell’s Kitchen and Chelsea on the banks of the Hudson River — is where you’ll find Edge. Suspended 100 stories above the city, it’s the highest outdoor observation deck in the Western Hemisphere. The glass floor and angled glass walls allow visitors to feel that they’re actually floating above Manhattan. Real daredevils can buy a ticket for City Climb, strap on a harness, and scale up the side of the building. 

The United Nations Educational, Scientific and Cultural Organization (UNESCO) has earmarked more than 1,100 cultural and natural wonders as World Heritage Sites worthy of preservation. You’ve surely heard of landmarks like Stonehenge or Machu Picchu, but what about the lesser-known wonders closer to home? From a prehistoric site in Illinois once home to 20,000 people to the world’s largest non-polar ice field, check out these eight underrated UNESCO World Heritage Sites to visit in the U.S.

Waterton-Glacier International Peace Park – Montana

Situated on the border of Montana and Alberta is the world’s first international peace park, commemorating the peaceful relationship between the U.S. and Canada. This UNESCO site — consisting of Alberta’s Waterton Lakes National Park and Montana’s Glacier National Park — was chosen for its ecological significance. In addition to a landscape that includes glaciers, prairie, and alpine forests, the park also features an abundance of distinctive flora and fauna. While most visitors are keen to catch a glimpse of the larger mammals — elk, grizzlies, and bighorn sheep, for example — there is also a rich variety of smaller creatures. Your chances of seeing the tiny pygmy shrew might be slim (it’s the size of a dime), but beavers, turtles, snakes, frogs, and several hundred bird species share this habitat with colorful lichens, ferns, and wildflowers.

Cahokia Mounds – Illinois

The Cahokia Mounds State Historic Site, located about 13 miles from St. Louis, was once the largest pre-Columbian settlement north of Mexico. At its peak around 1150 CE, the population at the settlement site was about 20,000 people, larger than the city of London at the time. According to UNESCO, it is a “pre-eminent example of the cultural, religious, and economic center of Mississippian culture.” The biggest mound is Monks Mound, which is also the largest prehistoric earthen structure in the Americas. It stands about 100 feet tall and covers nearly 15 acres. The onsite interpretive center offers a look at what life would have been like in the Cahokia Mounds settlement.

Papahānaumokuākea Marine National Monument – Hawaii

Papahānaumokuākea is the only mixed heritage site in the United States, meaning that UNESCO recognizes it for both cultural and natural purposes. This collection of islands and atolls lies 155 miles northwest of the main Hawaiian islands and covers almost 140,000 square miles of ocean habitat. Papahānaumokuākea is home to one of the deepest coral reefs in the world and has an abundance of endangered wildlife, such as Hawaiian monk seals and black-footed albatrosses. The site is also significant to Hawaiian culture: This is where the Hawaiian people believe that life originated and where spirits return after death. At least two of the islands contain evidence of ancient human settlements.

Chaco Culture Park – New Mexico

This UNESCO site was a ceremonial and political hub for the Pueblo peoples of the Four Corners, from approximately 850 to 1250 CE. Chaco is of particular note for its distinctive architecture and the complexity of its buildings. That such buildings were constructed in the harsh desert climate is even more impressive. Visitors can still trace their way through the carefully engineered roads, which linked each site. From studying the remains at Chaco, archaeologists have learned much about the advanced social structure of Chaco culture. In 2013, that the Chaco Culture National Historical Park was also designated an International Dark Sky Park, meaning it is an ideal spot to camp out and enjoy a view of the stars undisturbed by urban light pollution.

La Fortaleza and San Juan National Historic Site – Puerto Rico

La Fortaleza, now known as Santa Catalina Palace, is the home of the governor of Puerto Rico. It was originally built in 1540 as a fortress to protect the Spanish settlers of the small Caribbean island against raids from the local Indigenous population. Ironically, La Fortaleza was seized twice in its history, by the English in 1598, and by the Dutch in 1625. Through the centuries, additional fortified structures were added, and in 1983, UNESCO chose to recognize the site for its fantastic display of European military architecture, which has been adapted to its island location. A number of different styles — Renaissance, Baroque, and Enlightenment — all chart the history of the nations that sought and ultimately failed to control Puerto Rico.

Monumental Earthworks of Poverty Point – Louisiana

The name Poverty Point may come from a nearby 19th-century plantation, but the impressive series of monumental mounds in Louisiana date much further back. The five giant mounds and series of semi-elliptical ridges were constructed between 1700 and 1100 BCE. Archaeologists believe that the hunter-gatherer peoples used this area as a settlement but also as a ceremonial center. At one time, it was part of a vast trade network that expanded for hundreds of miles. Whereas many such sites have been redeveloped or heavily excavated, less than 1% of the land at Poverty Point has been disturbed, allowing visitors to appreciate its size and the work that went into building it.

Wrangell-St. Elias and Glacier Bay – Alaska

Alaska’s Wrangell-St. Elias and Glacier Bay National Parks combine with Canada’s Kluane National Park and Tatshenshini-Alsek Provincial Park to form a single UNESCO World Heritage Site, covering almost 38,000 square miles. The largest non-polar ice field in the world lies within the site’s borders, as do vast expanses of untouched forest, rugged mountains, and glaciers. Unsurprisingly, this wild land is a habitat for a variety of animal life, including caribou, grizzlies, mountain goats, and polar bears. Along the coast, visitors might spy humpback whales, porpoises, otters, and seals. Park management at both Glacier Bay and Wrangell-St. Elias work in partnership with local tribal management to protect both the natural and cultural heritage of the land and its people.

Hawaii Volcanoes National Park – Hawaii

Hawaii’s second UNESCO World Heritage Site contains two of the world’s most active volcanoes, Mauna Loa and Kilauea. Their level of activity has created an ever-changing landscape that also acts as a haven for rare birds, which has led to the park’s International Biosphere Reserve designation. Access to the park changes according to the local volcanic activity, but during an eruption, visitors often flock to lookout points where they can see fiery magma colliding with the ocean water from a safe distance. Visiting the park during quieter times affords more opportunities for hiking and driving the backtrails, and to see the spectacular geological formations created by millennia of activity.