Ready for a road trip you'll never forget? Set your sights on one of these adventurous stretches of highway that provide access to some of the most arresting scenery on the planet.
These are hands-on drives: none of our 10 picks will allow you to let your guard down or let cruise control do most of the driving.
But you'll be rewarded with travel panoramas few people ever get to see. Just remember to keep your eyes on the road, though.
Sure, the Stelvio Pass is no longer a secret. There's an Alfa-Romeo SUV named after the switchback-laden stretch of Italian tarmac bordering Switzerland, and hordes of drivers show up every summer to check out the road British motoring program "Top Gear" once called the greatest in the world.
But wake up early, and you'll find that the Stelvio's still a jaw-dropping drive worthy of your bucket list. Boasting epic views of the eastern Alps -- that is, when you can afford to look up from the road: there are 75 turns during the climb to 9,045 feet above sea level.
Big number: Three -- the number of languages (Italian, Romansh and German) that historically converged at Dreisprachenspitze peak, just above the route.
When to go: June to October, generally; check for road opening and closing dates.
Fly into: Zurich, Switzerland (ZRH) or Milan, Italy (MXP)
Sometimes referred to as "the road to the sky," the Transfăgărășan climbs from 1,630 feet to 6,700 feet. Alamy
This wild Romanian road that crosses the Carpathian Mountains has quite the backstory: depending on who you ask, it was built either to protect against the possibility of a Soviet invasion, or it was a folly, built by Nicolae Ceaușescu simply because he could.
Either way, hundreds reportedly died during dynamite blasts during construction in the 1970s. The result of their efforts is sometimes referred to as "the road to the sky" as the route gently climbs from 1,630 feet to 6,700 feet in elevation, with near endless hairpin turns (such a design would facilitate moving heavy military equipment.)
It's an engineering marvel: the 71-mile route required a mind-bending array of bridge crossings.
Big number: 1,480 -- the number of stairs that climb toward the 13th-century Poenari Castle where Vlad the Impaler, the inspiration for Bram Stoker's Dracula, lived. It's just off the route.
When to go: June to October, but be sure to check for road openings.
Fly into: Bucharest, Romania (OTP)
James W. Dalton Highway
Stretching from central Alaska to Prudhoe Bay, James W. Dalton Highway is one of America's northernmost roads. Jim Lo Scalzo/EPA-EFE/Shutterstock
This mostly gravel Alaskan road is one of the loneliest routes in the world -- and that's the draw. Only a quarter of the Dalton Highway's 414 miles from Livengood to Deadhorse are paved, and the travel can be rough going as the route traverses above the Arctic Circle, through the Brooks mountain range, and towards the Arctic Ocean.
The road was built in the early 1970s to assist the creation of an oil pipeline that runs along it, but it wasn't until 2009 and the TV show "Ice Road Truckers" that the road gained notoriety as a dangerous, though beautiful, drive.
You still won't find much traffic. Or food. Or support. There's just one rest stop on the road. Well-laid plans are a must and survival gear is recommended.
One note: the major car rental agencies won't allow their cars on the road; contact a specialist for SUVs that are prepared for the task.
Big number: 126 -- the mileage where you'll come across the "Oh Shit Corner," a particularly tricky curve for trucks travelling too fast.
When to go: mid-May to mid-September
Fly into: Fairbanks, Alaska (FAI)
Trollstigen ('Troll Ladder')
The "Troll Ladder" climbs at a 10% incline through an enchanted mountain landscape. James D. Morgan/Getty Images
Got Dramamine? You might need it before taking on Norway's famed Trollstigen, a road that climbs a 10% incline and makes 11 hairpin turns in the process of ascending a mountainous landscape befitting a troll-filled fairytale.
Along the way, you'll cross impressive waterfalls such as Stigfossen, over a thousand feet high. Near the top, there's a modern visitor centre where you can catch your breath.
Big number: 3,600 -- the number of feet of the straight vertical drop of Troll Wall, Europe's tallest vertical mountain wall, a short drive from Trollstigen.
When to go: May/June through October/November
Fly into: Oslo, Norway (OSL)
At more than 3,100 miles long, Ruta 40 is the longest road in Argentina (and one of the longest in the world).
Ready for the "big trip" -- the real deal, like-a-rolling-stone, once-in-a-lifetime wander? Set your sights on Argentina's Ruta 40, a national road that travels over 3,100 miles from La Quiaca, Jujuy in the north, which is near the Bolivian border, to Cabo Virgenes in Santa Cruz to the south.
The partially unpaved route is studded with national parks -- 20 of them -- and runs through 11 provinces, paralleling the Andes mountains and traversing stretches of wild and windy, remote Patagonia.
One-way car rentals are prohibitively expensive, so if you're doing the entire shebang, buying a used car and selling it at the end of the trip may be the way to go. Just make sure your ride is sturdy enough to chug across mountain passes including Abra del Acay, which, at 16,060 feet in elevation, is the highest road in the Americas.
Big number: 236 -- the number of major bridge crossings on the route.
When to go: September to November; April to May
Fly into: Rio Gallegos, Argentina (RGL)
The best things to do in Bariloche, Argentina
Pakistan and China
The KKH, as it's called -- or the eighth wonder of the world, depending on who you talk to -- covers 810 wildly high, wildly scenic miles along an old Silk Road path from Abbottabad, Pakistan to Kashgar, in Xinjiang, China, crossing the Himalayas, the Karakoram, and the Hindu Kush.
The 20-year project was finished in 1979, but it's not a polished modern route: many stretches are unpaved. Car rentals are rare. Many adventurous travellers get around the KKH via a patchwork of bus services, where you'll hear an impressive array of languages spoken.
A word of warning: note your country's travel advice to the region before planning a trip.
Big number: 15,397 -- the number of feet above sea level of the Khunjerab Pass, the highest international border crossing in the world. It's also the highest point on the Karakoram Highway.
When to go: May to October
Fly into: Islamabad, Pakistan (ISB)
North Yungas Road
North Yungas Road, sometimes referred to as "Death Road," saw more than 200 deaths a year in the mid-1990s. VW Pics/UIG/Getty Images
If you've spent a night shooting the breeze in a hostel anytime in the last couple of decades speaking to backpackers who have "done" South America, you've likely heard of the "Death Road."
The 40-mile Bolivian route became famous in the mid-1990s when the road was responsible for more than 200 deaths a year.
North Yungas drops nearly 12,000 feet as it winds from La Paz to Coroico in Bolivia, much of it cliffside. In 2007, a safer new route was opened to automobile traffic, and the old Death Road is now relegated mostly to mountain bikes.
To experience the still-deadly route (18 bikers have reportedly died since 1998), you can rent a cycle or join a tour through an operator like gravitybolivia.com.
Big number: 1,900 -- the number of feet of sheer drop-off on some stretches of the Death Road.
When to go: April to November
Fly into: La Paz, Bolivia (LPB)
Million Dollar Highway
Million Dollar Highway stetches across 82 miles in the rugged and remote southwest side of Colorado. Shutterstock
US Route 550 is a ribbon of road that drapes over 82 miles of the San Juan Mountains, running past three 10,000-foot passes in the rugged and remote southwest side of Colorado.
The most memorable miles are the couple dozen between Ouray and Silverton, where the million-dollar views are as epic as the driving can be harrowing -- limited guard rails and plenty of curves will have your passengers reaching for the grab handles.
Big number: 23 -- the number of species of evergreens you'll see on the roadside.
When to go: May to September
Fly into: Montrose, Colorado (MTJ)
Highway 340 gives you an intimate look at Maui's North Shore. Shutterstock
Traversing 20 treacherous miles of Maui's North Shore from Kapalua to Wailuku, Highway 340 gives you an intimate look at the area's countryside, the unique rainforests and the roiling sea below.
That is if you can manage to take your eyes off the road. And you probably shouldn't: Kahekili is barely more than a single lane wide. Blind curves and snaking pavement around cliffs and bridges demand full attention.
The reward is a hidden side of the Aloha State very few visitors get to see. If you come across another car, just remember that the inside traffic has the right of way.
Big number: 100 -- the number of feet the Nakalele Blowhole, a natural geyser just off the Kahekili route, can shoot seawater into the air.
When to go: April to May; September to November
Fly into: Kahului, Hawaii (OGG)
Atlantic Ocean Road
At just over five miles long, this dramatic, windswept stretch of road is the shortest entry in our list. Alamy
At just over five miles long, this dramatic, windswept stretch of road is the shortest entry in our list, but it's a crown jewel anyone with a sense of automotive wanderlust shouldn't miss.
Traversing an archipelago connecting the Norwegian town of Eide with the island of Averøy, the Atlantic Ocean Road ducks and bobs over 12 architecturally distinct bridges, which, depending on the time of year, you'll find shrouded in mist or smacked by full-on waves. (Check your windshield wipers before departing.)
The project was originally drawn up as a railroad route and was finished as a motorway in 1989. It's now a frequent backdrop for car commercials.
Big number: 12 -- the number of hurricanes that hit the Atlantic Ocean Road during its construction.
When to go: May to June; September to October
Fly into: Oslo, Norway (OSL)