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

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

The unusual patterns in this rock formation result from two distinct modes of weathering.

Hundreds of thousands of concrete bunkers crowd Albania long after the fall of Communism.

The elliptical citadel resisted the advance of the mighty Ottomans several times, thanks to the military prowess of the "Dragon of Albania."

A medieval bridge stretches over a sulfur-rich river that leads to year-round natural hot springs.

A naturally beautiful, seemingly bottomless deep blue spring.

One of the largest single-span stone-arch bridges in the Balkans looks like something straight out of a fairytale.

Flames have been burning within this mountain for more than 2,500 years.

This historic black and white monastery is one of Bulgaria's architectural jewels.

The largest axe on the planet contains a time capsule that seems like it may never be discovered.

A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.

The largest and most well-preserved petroglyph site in the Verde Valley.

This sinkhole in the Arizona desert is filled with carbonated, arsenic-rich water

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

This Route 66 classic sports a giant fiberglass rabbit that you can ride.

A unique collection of artistic rides

This public square capitalized on a single Eagles reference to bring some life back to an Arizona town.

One of the final grand railway depot hotel complexes is slowly being restored to its former glory.

This memorial includes fragments from one of the greatest tragedies in United States history.

This rusted car found in Petrified Forest National Park's Route 66 exhibit may be the most photographed abandoned car in the country.

The oldest continuously occupied public building in the United States.

This innocuous New Mexico storefront was once the secret jump-off spot for Manhattan Project scientists.

The Grand Canyon of Texas.