One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

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

An ancient Egyptian temple in the middle of Madrid, Spain.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

Mysterious Spanish catacombs of unknown origins.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

A huge cathedral single-handedly constructed by one eccentric monk.

Geological storytelling.

Cliffside houses provide a spectacular view from their perch above the valley.

"Alleys of Stone" form natural mazes in Spanish natural park.

12th-century holy complex shares land with a natural park full of heavenly waterfalls and raptors.

An impressive home made of stone, carved more than a century ago.

Numerous sculptures set along hiking trails symbolize and idealize the relationship between man and nature.

This awesome Spanish castle is so fantastical it was actually used on Game of Thrones.

This religious complex carved into a cliff is steeped in legends of miraculous stags and the Holy Grail.

Now a pile of ruins and rubble, this was a lovely mountain town as recently as 1960.

Archaeological site of Iberian people ruins.

A breathtaking canyon offers stunning views and frightful pathways through an ecological paradise.

Sanctuary on a ridge near an ancient shrine to a "Black Madonna" built by the founder of Opus Dei.

A site where “the ravages of the war are more striking…than any other place in contemporary Spain.”

A series of recreated fortifications mark George Orwell's path through the Spanish Civil War.

An independent naturist colony amidst 1000-year-old ruins.