The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

Religious structure known for its sculpted details.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

Romania's triumphal arch looks out over Bucharest.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

The bust of Romania’s most notorious ruler, Vlad Dracula aka "Vlad the Impaler," keeps watch over the ruins of his medieval court.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

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.

A hidden three-foot-wide house separates these two regal churches.

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

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.”

The world's oldest bookshop still in operation.

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

Extremely famous in his native country, this Cracovian painter is all but unknown beyond Polish borders.

In the summer, the area around this sculpture transforms into a vibrant concert venue.

The Polish capital has had a deep connection to its guardian mermaid for almost a millennium now.

Amsterdam's Red Light District leaves little to the imagination.

This still-celebrated home was a radical architectural experiment in 3D De Stijl.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

Rich with fauna and flora, nature-lovers can walk across the sea at this UNESCO World Heritage spot.