The world's brightest bioluminescent bay.

Legend tells how a Spanish soldier disappeared from this isolated sentry box without a trace.

This bleach-white graveyard overlooking the ocean is accessed through a tunnel.

This tiny home was originally a narrow alleyway.

This chapel on a cliff is renowned for its healing powers and was founded on the site of a supposed divine intervention.

This colorful gate stands as an entrance to the walled city of Old San Juan.

Puerto Rico's oldest rum producer started its 140-year-old business with "a little barrel."

The world's second largest single-dish radio telescope, once used to contact E.T.

This museum preserves the heyday of Puerto Rican coffee.

Rumored to be the famed pirate's lookout tower, this historic stone structure is now just watching for tourists.

A rare underwater observatory in the Caribbean that provides breathtaking views of vibrantly colored aquatic life.

A sharply wedged sundial marks the point at which each day in the United States begins.

Somber memorial to the May 10, 1933, book-burning which took place on this spot.

The final resting place of the famed German pilot, the "Red Baron."

This tremendous timepiece was once the largest cuckoo clock in the world.

The many—66 to be exact—faces of the German forest.

Legendary site where an evil bishop was devoured by rodents.

The final resting place for a wealthy Roman family, this tomb might be the best preserved of its kind outside Italy.

A poignant mural honors the heroic teenage non-conformists who took on the Nazis and paid the ultimate price.

The bones of the Biblical Magi traveled to Constantinople and Milan before landing in their current home inside an elaborate golden reliquary in the Cologne Cathedral.

This statue has a painful history, but activists have since recontextualized it as a way to educate visitors about the dangers posed by fascist regimes.

One of the most well-known city festivals in the world.

This bomb was once used as a church after it failed to detonate.

Remnants of a cone-shaped Nazi bomb shelter.