Scattered throughout London are ancient remnants of the city's former bounding wall.

Eighty million natural history specimens call this gargantuan museum home.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

A whimsical brother of the nearby Fallen Angel statue takes the falling part quite literally.

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

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

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

Commonly acknowledged as the only public monument to the Devil himself.

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

This influential Renaissance-era library was once the haunt of kings and monks.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

This castle has links to Portugal’s founding and struggles for independence.

Portugal's National Pantheon has a history of curses, collapses and financial problems.

The corpse bride of Portugal.

Elaborate tile work in this railway station tells the story of Portugal.

A stunning 18th-century site where pilgrims ascend by a series of punishing stairs only to return via funicular.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

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

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

The world's oldest bookshop still in operation.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

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