The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

A spectacular rainbow of stained glass makes the "Pink Mosque" one of the most beautiful in Iran.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

A public urinal so pretty, it was declared a national monument.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

Debatably clever, or just plain honest hotel advertised as "The Worst Hotel in the World."

A beautifully eclectic mix of architectural styles.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

This Berlin island is home to a flock of free-roaming peacocks, as well as a historic ivory folly.

A dreamy mausoleum honors Persia's most famous poet.

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

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

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

An eerie collection of the surviving structures from a past celebration of the future.

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

The world's largest wooden structure.

This small chapel is built of human bones and decorated with a golden skeleton.

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

The world's oldest bookshop still in operation.

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

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

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