The vast, legendary catacombs hold secrets much stranger than stacked bones.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This bridge was constructed from the rubble of the infamous Bastille.

The celebrated eyesore created by starry-eyed sweethearts.

Climb inside an iron crystal magnified 165 billion times its normal size.

The final resting place of the great navigator, or maybe his brother.

Spain's largest bullring offers a unique glimpse at architecture and history.

The world's largest wooden structure.

Perhaps the most spectacular grotto along the Algarve coastline.

One Portuguese poet described this cape, the westernmost point in mainland Europe, as "where the land ends and the sea begins."

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

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

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.”

Giant topiary dog once played a role in a terrorist bomb plot.

This amazing example of Valencian Art Nouveau looks more like a cathedral than a public market.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

The facade of this 16th-century building is decorated with carvings of 300 seashells.

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

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

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

This unassuming bookstore in the heart of Madrid is one of the oldest in Spain.

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