Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

One of the world's first dedicated bank buildings in the world is now the oldest one.

A plaque marks the house in Stockholm where the French philosopher René Descartes lived up until his death.

This gem from the industrial age helps visitors and residents alike traverse hilly Stockholm.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

This unique sculpture is often overlooked by pedestrians.

Sweden's oldest animated sign is still lighting up the skyline today.

It houses the remains of a 17th-century version of the Titanic.

A brush maker used his factory to protect blind Jews from the Gestapo.

Everyone from Alan Ginsberg to The Rolling Stones has stopped by this classic dive bar.

A tribute to the statues of Easter Island along Route 66.

The remains of Abó, Gran Quivera, and Qurai are monuments to the long, complicated history of the Indigenous people of the Southwest.

This is one really big nut.

The final resting place of the living embodiment of the famous Forest Service symbol.

Hidden in the New Mexico desert southeast of Roswell, nine small deep lakes formed inside sinkholes.

This sculpture is intended to reset a person’s creativity.

A cave's rare beauty held a cavernous secret hidden underground.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

Steep canyon walls hide a forested oasis in the West Texas desert.

Every year, the colorful murals of Montreal get a complete makeover.

100 massive sculptures in the Hudson River Valley.

The world’s largest concentrated solar plant generates as many problems as megawatts.

A memorial to the unknown and unheralded men and women of the Cold War military and intelligence services.

Formerly the world's largest, this Willy Wonka-esque contraption runs 24/7.