The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

Come for the flowers, stay for the bats!

Curious crater remnants in the middle of the Australian outback.

Olive’s garden serves up a seemingly endless helping of outback delights.

A spectacular impact crater in the rugged heart of Central Australia.

A graceful natural rock formation stands astride the point where the Gulf of California meets the Pacific Ocean.

The highest tides in the world come in and out here twice a day, allowing you to essentially walk along the ocean floor.

Enormous small-business mecca in the Midwest, serving dozens of artists.

One man's attempt to create an artistic wonder on a run-down block in Detroit.

What is it about mushrooms that makes people wish they lived inside of them?

A tunnel with windows, so you don't miss out on the impressive views.

The fifth-longest natural arch in the world, and the longest outside China.

A house carved into a rock in the 1940s.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

An earthwork sculpture built by Robert Smithson in the Great Salt Lake only reemerges during drought.

The longest navigable underground river in the United States is home to countless blind and albino animals.

An obsolete, vanishing traffic device warns Cincinnati drivers away from middle-of-the-road obstructions.

Rare recess caves fill this unbelievably beautiful Ohio park.

The largest earthwork effigy in the world.

One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

The "mysteries" of this quintessential roadside oddity were almost destroyed by neglect but were saved by fans of kitschy wonder.

The entrance to this sinisterly named tunnel hides behind a Tim Hortons.

Now in disrepair, this 19th century station was a stop on of the famed B&O Railroad.