A subterranean relic of the Spanish Civil War hides below this picturesque park.

Stuck in the middle of a modern Madrid city block are the remains of a 19th century sports complex.

Among the oldest structures in Madrid, these Moorish walls once guarded the medieval city of Mayrit.

This amazing abuela became a diehard metal fan late in life and an icon of Madrid's '80s rock scene.

The morbid items in this small and hidden museum are not for the weak stomached.

The earliest known map to show America, discovered by accident at a Paris bookshop.

This funky former tobacco factory is one of the most striking examples of Madrid's cultural diversity.

A lush indoor jungle fills this bustling Madrid transportation hub.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

Single runway interrupted by a busy road that cuts across its middle.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

The best place in the world to buy tinned fish.

An early Portuguese serial killer's head is alarmingly well preserved in a jar at the University of Lisbon.

This charming candle shop has been in business since 1789.

Hidden beneath a beautiful overlook you’ll find the history of the city depicted in comic strip format next to a pay toilet.

Located in the thermoelectric factory that once powered the entire city, this Portuguese museum is shockingly fascinating.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

The majority of the museum's large collection is held in a storage space open to the public a few times a year.

An alleyway plaque is all that remains of the independent Texas' envoy that forgot to pay their rent for over a century.

An American ghost town hides along a side street in Scotland's capital.