This unique building in the main square stands out among the city's typically Baroque architecture.

This church is named for one of the most dramatic tales in the early Christian church.

This strange moor has a song written about it, Bronze Age carvings, and an alien sighting.

This building was once a town hall, a fire station, a prison, a dairy market, and the target for two marksmen.

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

This museum housed in a former brothel explores the past and present of sex work in Amsterdam.

This giant wooden treehouse within a sprawling garden has its own eatery.

19th century museum with an eclectic mix of curiosities, from Egyptian artifacts to items on archery history to the skull of the world's oldest horse.

A slightly creepy gallery of plaster cast models in the same museum as Michelangelo's David.

The mastermind behind this palatial hotel perished on the Titanic weeks before its grand opening.

Louise Bourgeois' 30-foot-tall steel spider sculpture.

An Iron Age fort on the edge of a seaside cliff offers a glimpse into an ancient, mystical world.

This World War II relic let Allied pilots know they were entering neutral airspace.

It was once nicknamed "the most bombed hotel in Europe."

Former headquarters of the KGB.

Dozens of padlock-trees along the Moscow River.

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

Stalinist skyscraper built with help of cryotechnology.

Gargantuan home of Russian science.

An 18th century wonder of the world, lost in WWII, re-created at the Catherine Palace.

Perhaps the tiniest sculpture in Saint Petersburg is a little bronze finch inspired by a song.

This arch granting triumphal entrance into Antalya was designed to honor the emperor's visit.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

This charming Latvian lane doubled as Baker Street on the Soviet Union’s version of Sherlock Holmes.