Bizarrely shaped rock formations in northwest Bulgaria come with equally bizarre legends.

A massive cave once a secret military base is now home to thousands of bats.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

An homage to the medieval rulers of Bulgaria.

An architectural marvel that spans the Arda River, and has stories of a haunted past.

This massive stone and steel monument remembers a century-old battle that cost thousands of lives and nearly destroyed the city.

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

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

Named after an outlaw who used the basin as a hideout.

This former open-pit manganese mine is now a massive graffiti canvas.

A memorial to the unknown and unheralded men and women of the Cold War military and intelligence services.

A private Las Vegas horse ranch adorned with whimsical artwork.

A Norwegian-born sculptor created these soaring guardian angels at the entrance to Hoover Dam.

These huge stone ovens in the desert fueled the Nevada silver boom, and may have also been a hideout for outlaws.

An overlooked monument to the celebrity gangster who helped put the sin in Sin City.

Las Vegas's very own 40-foot-tall fire-spewing praying mantis.

This vintage animatronics show is the Vegas version of a walk through the woods.

Nearly 300,000 acres of wildlife, natural splendor, and a hidden ghost town have been designated a national monument.

An exotic wildlife habitat right off The Strip.

Thousands of artifacts relating to human sexuality, including the world's largest sex bike.

The longest living non-clonal organisms on Earth.

The neon signs from Las Vegas' past find their final resting place at this unusual graveyard.

Stepping away from the glitz of mobsters and casinos to learn about the other history of Vegas.

This sign designates the road that leads to the infamous Area 51.