Giant topiary dog once played a role in a terrorist bomb plot.

Now an entertainment complex, the Lingotto building was once an avant-garde auto factory with a test track on the roof.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

From carts to cars, this leftover Roman bridge in France has managed to survive for centuries.

360° views of the city plus five floors of optical illusions and hands-on science.

Air Force Academy Chapel made of 100 identical tetrahedrons works to inspire those of all religions.

At the tallest peak in Colorado, an electrifying mix of thin air, lightning, and rivalry.

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

See massive fossils that are over 200 million years old in northeastern Arizona.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

Twenty-seven massive radio antennas on the high plains of New Mexico search for life on other planets.

One man's exploration of the human form, including the bizarre and delightful "Man Attacked by Babies."

The highest peak in the United Kingdom has a history of physics, specters, and a pilgrimage of strange objects.

Ancient snack bar of the Roman Empire re-opened.

Erotic art covers the walls of the largest ancient pleasure palace.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

The library of every book lover's dreams.

The only road through the heart of Glacier National Park.

A beautiful geyser under environmental threat.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

A smoke stack so large, the Washington Monument could fit inside!

New fungal and bacterial species call this deadly lake home.

Art Deco and “Wrenaissance” mash-up, this recently restored royal residence has been home to kings and comes with secret monkey passages included.