Since its original beginnings as a weather observatory mountaintop, this facility played an instrumental role in gathering atmospheric data for almost 100 years.

The highest point in Washington state is a volcano covered in glaciers.

This long, dark tunnel is open to hikers, but those without lights are known to get confused even on the straight path.

Former farm staffed by mental patients is now a public park.

The illuminated falls are a gem in North Cascades National Park.

This handsomely carved wooden church is more than 800 years old.

Dedicated to the life of a brave woman soldier.

A plaque on the base of this statue holds a bewitching design.

A standalone wonder amid the prairie badlands of southeastern Alberta.

The most impressive of Basel's three remaining city gates.

This park is home to a massive bird sanctuary.

A tunnel that brings more than a century of history to life from the deepest parts of the Niagara Gorge.

A 12th-century castle featuring a sensory path where partially-sighted visitors can experience regional history through touch and sound.

This exaggerated sculpture resembles a well known feature of Vancouver:

Along the Outback Scenic Byway, adjacent to hot springs, this human-made geothermal feature takes unexplained breaks.

Made of granite, this is a symbol of the Inuit peoples near water that expresses abundance.

This Civil War monument was designed by an eccentric architect and Gettysburg veteran.

The second-largest giant sequoia in the world.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

A 1930s Art Deco swimming pool with a design inspired by grand ocean liners.

This unique museum focuses on the Siege of Sarajevo through children's eyes.

This historic timepiece is thought to be the only public clock in the world that keeps lunar time.

This mysterious tower is said to enshrine a dormant seven-headed serpent that once protected Vientiane from destruction.

Perhaps the only one of its kind, the nearly-forgotten site once held mortal (and rigged) gladiatorial games between tigers and imperial war elephants.