These cascading falls resonate throughout the Bulgarian forest.

The Grand Mall in Varna hosts one of the biggest collections of Soviet-era paraphernalia in Bulgaria.

A gigantic statue of a Russian soldier watches over the ancient city of Plovdiv, a prominent reminder of the Soviet period in Bulgaria.

Rock carving created 1,300 years ago 75 feet off the ground.

The remarkably well-preserved final resting place of a powerful ancient Thracian king.

UNESCO-protected ancient burial ground.

The second-largest Jewish temple in Bulgaria was deserted after World War II, seized by the communist government and then abandoned again.

In Chicago, a pizza-enthusiast has opened a museum dedicated to the history of pizza.

Hidden on the 7th floor of a historic building, this Cajun spot features wall-to-wall bottles of hot sauce.

Once at the center of U.S. finance, the historic Trading Room was meticulously recreated piece by piece and rebuilt in the Art Institute.

A Japanese temple, old German townhouses, and public chess tables offer a peaceful escape from the bustle of the North Side.

One of the few remaining relics of the meatpacking hub that made Chicago the "hog butcher to the world."

A goddess-topped water fountain in Chicago was created thanks to the dreams of a thirsty newsboy.

Orthodox church partially financed by Tsar Nicolas II.

This historic-shipwreck-cum-diving-spot can still be seen poking its boiler out of the Lake Michigan waters that claimed it.

The final resting place of up to 6,000 Confederate soldiers, the largest mass grave in the Western Hemisphere.

An outdoor urban gallery of large-scale artworks by the world's most influential street artists.

This surprising gem is a world-class archeological museum hidden at the University of Chicago.

The iconic Chicago sculpture hides a beautiful and easily overlooked plaque on the backside.

Home to a protest movement, a bombing, and a dramatic change in labor history.

The 606 is a decade in the making.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

One-of-a-kind preserved ruins of an abandoned 1880s church in Chicago's Pilsen neighborhood.