1

Seattle Underground City

Did you know the remnants of Seattle's original streets are still accessible? Beneath the bustling streets of modern-day Seattle lies the Underground City , a network of subterranean passageways that formed the ground level in the 1800s.

By the end of the 19th century, after the Great Seattle Fire, it was decided to rebuild the city at a higher elevation to combat frequent flooding . So, these original streets, sidewalks, and storefronts were buried, and with it, much of their history.

Guided tours take people through tunnels and ladders and retell real and eerie stories about the history of the Underground City.

2

Luray Caverns

Image: Robert Thiemann

Have you ever heard of the underground Stalacpipe Organ ? Not only is it a one-of-a-kind interaction between keyboards and cavern stalactites, but it is also the largest musical instrument in the world, according to Guinness World Records.

This instrument lives in the Luray Caverns, Virginia. It consists of an electric console that taps on these ancient stalactites of varying sizes to produce musical tones. A subterranean wonder, these caverns are also known for their extraordinary size , housing towering stalactites and stalagmites, mirrored pools, and delicate drapery-like calcite formations.

3

The Underground Gardens of Baldassare Forestiere

Image: Adrian Botica

This stunning subterranean retreat was built entirely by hand. Tucked under the sun-scorched landscape of Fresno, California, lie the Underground Gardens of Baldassare Forestiere . They are the life’s work of Baldassare Forestiere, a Sicilian immigrant who started digging in the early 1900s to escape the Central Valley's oppressive heat.

Over 40 years, drawing inspiration from ancient Roman catacombs , Forestiere carved an elaborate network of underground rooms, passageways, grottoes, and courtyards that span 10 acres.

A unique masterpiece, the gardens are open with guided tours that lead guests through beautifully designed spaces featuring skylights, arches, and alcoves. This oasis also boasts an array of fruit trees, including citrus, figs, and olives.

4

Ruby Falls

Image: Goodfreephotos_com

Colorful and breathtaking, the Ruby Falls is a geological wonder located inside Lookout Mountain near Chattanooga, Tennessee.

Hidden over 1,000 feet below the mountain's surface, this waterfall cascades 145 feet into a pool , making it one of the tallest underground waterfalls open to the public.

Visitors enter the mountain and descend via elevator. Then, they walk through stunning cave formations such as stalactites, stalagmites, and flowstone. At the waterfall chamber, multicolored lights –powered by renewable energy– illuminate the falls. Lantern-lit tours are also offered as a chance to visit the marvel with a different charm.

5

The Catacombs of Green-Wood Cemetery

Image: Joy Ernst

Arched tunnels of tranquil, sacred vaults lie beneath the Green-Wood Cemetery in Brooklyn, New York. Built in the mid-19th century, these catacombs were designed as a prestigious resting place for the city’s elite , prominent families.

While the catacombs are typically closed to the public, special events are sometimes organized to welcome visitors, such as art expositions, guided history tours, and candlelit tours seasoned with live music and storytelling.

Outside, where the sun does reach, await the serene landscapes and remarkable monuments of the cemetery, which is itself a National Historic Landmark .

6

The Lost Sea

Image: Roberto Nickson

The largest underground lake in America is in Tennessee. Hidden within the Craighead Caverns in Sweetwater, this enormous body of water lies in a cave system filled with fascinating formations, such as stalactites, stalagmites, and rare anthodites, also known as "cave flowers."

A National Natural Landmark, this lake marvels scientists, who are yet unaware of the exact extension of its waters. Those who visit can embark on a boat ride called "The Lost Sea Adventure," first walking inside the cavern before reaching a boat to navigate these ethereal sights.

7

Mammoth Cave National Park

Image: Sherin Jacob

The Mammoth Cave National Park is home to the longest cave system in the world . Located in central Kentucky, it extends over 420 miles of explored passages and many more likely undiscovered. Enormous chambers, underground rivers, a labyrinth of tunnels, and gypsum crystal formations can all be found at this site.

The park has been declared a UNESCO World Heritage Site and an International Biosphere Reserve. It also includes over 52,000 acres of protected land on the surface, renowned for its lush forests and diverse wildlife.

8

Carlsbad Caverns National Park

Image: Cason Asher

A large bat colony lives in the Carlsbad Caverns National Park in New Mexico, but that’s not its only charm. The park boasts over 100 caves, with its centerpiece being the immense Carlsbad Cavern.

The cavern includes the Big Room, one of the largest underground chambers in North America, spanning 8.2 acres. Visitors can descend via an emblematic natural entrance or by elevator, dropping 750 feet underground. Stalactite formations like the Giant Dome, the Hall of the White Giant, and the Chandelier are some of the caves' breathtaking highlights.

9

Indian Echo Caverns

Image: Magda Ehlers

The Indian Echo Caverns, which have been open to the public since the early 1920s, are carved into the limestone of the Appalachian Mountains. Located near Hummelstown, Pennsylvania, this site gets its name from the echoes heard within the cavern’s chambers , which were once believed to be mystical by Native American people in the area.

Unique, immersive sections of the caverns have names like the "Crystal Palace," the "Echo Room," and the "Wedding Room," where, yes, real weddings are sometimes held!

10

Wind Cave National Park

Image: Francesco Ungaro

Wind Cave National Park, located in the Black Hills of South Dakota, is one of the world’s largest caves, but that’s not what it’s most famous for. One signature sight here is the boxwork formation , a rare lattice-like pattern formed by calcite deposits.

The cave system stretches for over 140 miles, though much of it remains unexplored. Popular tours take guests through captivating features like the "Ribbon Room" and the "Crystal Palace."

Why is Wind Cave called that? Mainly due to the "wind" phenomenon that occurs at its entrance. The cave's air pressure causes the entrance to draw in or expel air, depending on atmospheric conditions.

1

Great Basin National Park, Nevada

Image: Yura Lytkin

Tucked away in eastern Nevada, Great Basin is the park that time forgot—in the best way possible. You can hike to a glacier, explore underground caverns, and camp under skies so dark you’ll see stars you didn’t even know existed , all without waiting in line or fighting for a decent photo spot.

2

Congaree National Park, South Carolina

Image: Selma Rizvić

This park protects one of the largest remaining expanses of old-growth bottomland hardwood forest in the United States, which is a fancy way of saying it's got trees so tall and old they make you feel like an ant at a giant's picnic. The real magic happens at night, when the fireflies put on a light show that'll make you forget all about mosquito bites. Plus, you can rent a canoe and paddle through what feels like the set of a Southern Gothic novel—Spanish moss and all.

3

North Cascades National Park, Washington

Image: Pete Alexopoulos

With jagged mountain peaks and more than 300 glaciers, this park offers scenery that’ll make your camera work overtime . The hiking ranges from "pleasant afternoon stroll" to "why did I think this was a good idea?" so there's something for everyone, assuming everyone likes being surrounded by absurdly gorgeous wilderness.

The best part? While everyone's fighting over hotel rooms near Mount Rainier, North Cascades sits there looking spectacular with hardly anyone around. The park sees fewer visitors in an entire year than Yellowstone does on a busy weekend.

4

Dry Tortugas National Park, Florida

Image: Nick Rickert

Located 70 miles off the coast of Key West, Dry Tortugas takes "off the beaten path" to a whole new level: you literally need a boat or seaplane to get there. The turquoise waters are so clear you could see fish judging your swimming technique from 30 feet away . Plus, there's Fort Jefferson, a massive 19th-century fort that feels like someone plopped a Civil War–era fortress in the middle of paradise and said, "Sure, that works."

Just remember: there’s no fresh water (hence the "Dry" part), no food service, and no shade except what you bring yourself. It’s like camping, but surrounded by the kind of blue water that makes you understand why people write songs about the ocean.

5

Guadalupe Mountains National Park, Texas

Image: Ryuta F.

Home to the highest peak in Texas (Guadalupe Peak at 8,749 feet), this park offers hiking that'll remind your knees they're not as young as they used to be, but in a rewarding way. The fall foliage in McKittrick Canyon is legitimately stunning , which surprises people who assume Texas is all tumbleweeds and barbecue joints.

The park sits on an ancient fossil reef from when this whole area was underwater, mind-blowing, if you think about it for more than two seconds. There’s no cell service, limited facilities, and the nearest town is about an hour away, which may sound like a complaint, but it actually forces you to unplug and take in the amazing place around you.

6

Voyageurs National Park, Minnesota

Image: Vyacheslav Makushin

Voyageurs is a water-based park that’s basically a summer camp for adults who can legally drink beer. With over 200,000 acres—about 40% of it water—houseboating is the way to experience it.

The fishing here is legendary, the northern lights make regular appearances, and in winter, the frozen lakes become highways for snowmobiles and cross-country skiers . It's remote enough that you feel like an explorer, but accessible enough that you won't actually die if you forget your matches.

7

Black Canyon of the Gunnison National Park, Colorado

Image: Dustin Weist

Colorado has so many stunning places that Black Canyon somehow gets overlooked. This canyon is deep, narrow, and so dramatically steep that parts of it only get 33 minutes of sunlight a day . The Gunnison River carved through 2 billion years of rock to create towering walls that make you feel appropriately insignificant, which is good for the soul occasionally.

8

Isle Royale National Park, Michigan

Image: Ivan Vashchenko

If you want to really get away from it all, Isle Royale is your jam: an island in Lake Superior that requires either a ferry ride or a seaplane to reach. Once you’re there, you’re committed; same-day visits aren’t really a thing. The park is car-free, crowd-free, and home to a fascinating wolf-and-moose study that’s been running since 1958.

The hiking trails crisscross the island through forests and along rocky shorelines where the lake looks more like an ocean . Backcountry camping is the main event here, and the solitude is so profound you'll hear sounds you forgot existed—like actual silence.

9

Pinnacles National Park, California

Image: Cyrus Crossan

California's newest national park is a playground of volcanic spires, talus caves, and rock formations that look like a giant was playing with clay and just walked away mid-project . The rock climbing here is world-class, and the cave exploration doesn't require any special gear—just a flashlight and a willingness to squeeze through some tight spaces.

The spring wildflower displays are spectacular, and the park is one of the best places to see the endangered California condor, which has a wingspan that makes eagles look modest. It gets hot in summer—and by hot, I mean "surface of the sun" hot—so plan accordingly.

10

Lassen Volcanic National Park, California

Image: Robson Hatsukami Morgan

This park sits on top of one of the world’s largest plug-dome volcanoes—and yes, it could erupt again—Lassen Peak last blew in 1915, which in geological time is basically yesterday. But don't let that stop you from enjoying the bubbling mud pots, steaming fumaroles, and hot springs that make you feel like you're walking on another planet .

The hiking is fantastic, with everything from easy boardwalk strolls through geothermal features to challenging climbs up Lassen Peak itself. Add in alpine lakes, wildflower-filled meadows, and a fraction of Yosemite’s crowds (despite being just a few hours south), and you’ve got a spectacular California secret.

1

Tipping is expected, not optional

In the U.S., leaving a tip is considered part of the cost of the meal, not a bonus . Diners typically add 15 to 20 percent to the bill, especially in full-service restaurants.

This practice exists because many servers earn lower base wages and depend on tips. In many other countries, service charges are already included in the bill, making the American system feel unusual or even confusing.

2

Free refills are the norm

Many American restaurants offer unlimited refills on soft drinks, iced tea, and coffee . Once you order a beverage, it often keeps coming at no extra cost.

Elsewhere, each drink is typically billed separately, and refills are rarely free. For visitors to the U.S., this can feel surprisingly generous compared to their dining experiences at home.

3

Ice comes with everything

In the U.S., drinks are often served filled with ice, whether it’s soda, water, or even juice . It’s considered a refreshing standard, especially in warmer climates.

In many other countries, ice is used sparingly or avoided altogether. Some people prefer drinks at room temperature, making the American preference for ice stand out immediately.

4

Portions are huge

American restaurant portions are known for their size. Many meals are large enough to serve more than one person or to provide leftovers for later .

In contrast, other countries tend to serve smaller, more balanced portions. The American approach reflects a culture of abundance, but it can be unexpected for first-time visitors.

5

Taking leftovers home is typical

Asking for a take-home container, also known as a "doggy bag," is a normal part of dining in the U.S. Restaurants are prepared for it, and many people expect to leave with leftovers.

In some countries, this practice is less common or even discouraged. The American "doggy bag" reflects both larger portion sizes and a practical approach to reducing food waste.

6

Waiters check in frequently

In the U.S., servers often return to the table several times during a meal . They may ask how everything tastes, refill drinks, or check whether anything else is needed.

While meant to be attentive, this can feel intrusive to foreign visitors. In many other cultures, less interruption is preferred, and diners typically signal the server only when necessary.

7

Customizing your order is normal

In the U.S., it's common to request changes to a dish, such as removing ingredients or adding extras . Restaurants are usually flexible and expect these requests.

In other parts of the world, altering a menu item may be frowned upon. The American habit reflects a strong emphasis on personal choice and individual preferences.

8

Tap water is served automatically

In American restaurants, a glass of tap water is often brought to the table without being requested . It is typically free and refilled throughout the meal.

In many other countries, bottled water is the default and must be ordered separately.

9

Meals tend to move quickly

Dining in the U.S. often follows a faster pace. Food arrives quickly, and the bill may be brought shortly after the meal is finished .

In contrast, in many other cultures, meals are meant to be long, relaxed experiences. The American approach reflects efficiency and a faster daily rhythm.

10

Splitting the bill is common

In the U.S., restaurants commonly allow separate checks , making it easy for each person to pay their share. This is especially helpful in group settings.

In many other countries, splitting the bill can be more complicated or is actively discouraged. The American system emphasizes convenience and individual responsibility at the table.

11

Sweet foods are common at breakfast

Breakfast in the U.S. often includes sweet items such as pancakes, waffles, pastries, or cereal, alongside eggs, bacon, and toast. Syrup and sugar are common additions at the start of the day.

In many other countries, breakfasts tend to be exclusively savory, featuring foods like bread, cheese, or eggs. The American preference for sweetness can feel like a treat to visitors.

12

Dining is generally casual

While there are many exceptions at five-star, fine dining establishments, American dining culture is typically relaxed, with fewer formal rules about dress or behavior . People often eat out in casual clothing and informal settings.

In other countries, meals, especially dinner, can be more formal events. The American style reflects a focus on comfort rather than tradition.