The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

This once-derelict building is now one of the most beautiful bookstores in the world.

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

The kitsch mansion of the former Romanian president Nicolae Ceaușescu features a golden bathroom.

Romania's triumphal arch looks out over Bucharest.

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

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

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

An architectural statement of artistic intent smack in the middle of Providence, Rhode Island's Colonial uniformity.

A simple Colonial home with a past haunted by death and madness.

Macabre astrological automaton clock dating to the late 1400s.

This ancient theater was once the home of fierce gladiatorial battles.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

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

The fairy tale castle of the “fairy-tale king,” this was also the inspiration for Disney’s “Sleeping Beauty.”

These mysterious Viking chess pieces spent centuries hidden on a remote Scottish island.

This marine reptile was discovered by one of the 19th century's greatest fossil hunters.

The "lost friend” is the most famous of the six moai statues that were removed from Easter Island.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

A collection of comics, graphic novels, animation and caricatures devoted to exploring this often overlooked art form.

A grand entrance to one of the world's smallest Chinatowns.

The striking jade death mask of an ancient Maya king is displayed in a replica tomb in Mexico City.

Once home to an aristocratic family and a workers' organization, this intricately tiled building now houses a chain restaurant.