Berlin's old airport.

A 12th-century fortress containing some of Berlin's oldest buildings.

Someone loved this song enough to carve all of its lyrics onto a tree trunk in a Berlin park.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

A tree-like building perches on its trunk in the Steglitz neighborhood of Berlin.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

Art and a pun, all in one.

A state-of-the-art medical facility from the Imperial era is now a derelict ruin.

An eerie, derelict amusement park in Berlin.

The patron of this extravagant Art Nouveau confection insisted that nothing less than a boat should project from its facade.

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

The last of Amsterdam's original sea level markers remaining in place.

Amsterdam's narrowest house facade is a monument to 17th-century tax evasion.

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

Seven mini rowhouses fill the gap between 54 and 70 Westerstraat.

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

The attic of a four-century-old canal house hides a clandestine church.

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

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

A floating cat sanctuary on an Amsterdam canal.

Lavish royal estate punctuated with heated greenhouses.

A Byzantine church containing the holy remnants of three saints sits atop the site of an ancient temple.