This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

This large, circular tomb is the final resting place of the first emperor of Rome.

This hydrochronometer was invented by a Dominican monk and is a prime feature in this garden.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

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

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

A forgotten "city of water" underneath the famous Trevi district.

This ferry carries passengers across the Rhine propelled by no engine or paddles but by the river's current.

Founded by members of the Tohono O’odham Nation, this one-room joint's James Beard–winning fry bread is light as a cloud.

The "Father of Arizona" tried to build a Zoroastrian fire temple on the hill where he's now buried.

At an isolated roadside rest area stands a monument marking where famous Western star Tom Mix died in 1940.

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

A reproduction of earth's many biomes.

The outcropping is graffitied with the name of the beloved musical Muppet television series.

At this research institute, the chile is king.

This site honors the end of a 100-year boundary dispute between the United States and Mexico—all started by a river's shifting course.

A Texas cave network is home to some of the world's most spectacular-looking and bizarrely named mineral formations.

A colorful public mural in San Antonio's West Side encourages students to stay in school.

The 40-foot-tall votive candle is the largest of its kind.

A mother's mourning for her lost son is remembered in this small park embedded with his memory.

Tile mosaics and quotes from Pablo Picasso add an artistic flair to these bus stop benches.

This big empty pig is a nostalgic throwback to mid-20th-century Texas barbecue.

The quirky gift from West Berlin for the 1968 World's Fair still stands in Hemisfair Park.

Craggy concrete faces are hidden in the walls of this artificial cave along the San Antonio River.