A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

Jesus' footprints and the first catacombs in the world.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

Stairs often replace streets on the steep slopes of this old mining town.

The world's only teal arches exist in a city that cares more about its aesthetic than an Instagram influencer.

Some of the tallest ancient American ruins continue to inspire awe and curiosity.

This balancing rock is one of Utah's most unusual geological formations.

These tall, red sandstone pinnacles outside Moab are often forgotten amid their more famous neighbors.

The location where the iconic movie character declared it was time to go home.

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

A house carved into a rock in the 1940s.

At this Denver landmark, the meals are compulsory, the sopapillas are complimentary, and the insanity is everywhere.

This volcano rises like a giant anthill from the plains below, with a road spiraling up to the rim.

The short-lived history of a new republic and British control in West Florida.

This ancient settlement contains some of the largest earthen mounds in North America.

The tallest monument in a historic New Orleans cemetery was prompted by romance and dash of pettiness.

This distinctive Crescent City tradition dates back to the days of horse-drawn carriages.

A swamp and garden tour featuring local wildlife and exotic botanical specimens from around the world.

The oldest family-run restaurant in the United States is a living museum of New Orleans dining history.

New Orleans' famous cemetery, located on the site of a former race track.

A theme park that suffered massive flooding during Katrina was abandoned, and now proves irresistible to trespassing explorers.

The second-largest ceremonial mound in the United States is an artificial hill that is loosely shaped like a pentagon.

The site of the notorious Camp Sumter Prison is now a peaceful memorial.

Once seen as a bit of an eyesore, this sculpture has become a staple of downtown Houston.