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

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

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

A floating cat sanctuary on an Amsterdam canal.

The world's only museum devoted to the wonders of fluorescence.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

Fall down the rabbit hole into a surreal journey of human consciousness "from ass to soul."

Visitors can explore the role of mysticism throughout the ages inside this interactive museum of magic.

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

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

An abandoned NSA listening post on Berlin's "Devil's Mountain."

Art and a pun, all in one.

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

An eerie, derelict amusement park in Berlin.

Located near Cairo's El Korba district, the abandoned mansion continues to inspire mystery and rumor throughout the city.

Standing atop 2nd-century Roman ruins, this church is one of the oldest and most iconic in Old Cairo.

A preserved oasis with traditional Andalusian-style architecture and beautiful views of the Nile.

An incredible mosaic-lined monument said to have held the remains of an ancient Roman empress.

A lonesome Moai stands in a small Italian town some 9,000 miles away from its Easter Island brethren.

A lavish 16th-century mansion filled with spectacular staircases, fantastic frescoes, and gorgeous gardens.

Two planes stand abandoned after the closure of an aircraft-themed restaurant.

Massive galleon from a box-office bomb docked in Genoa.

A 2,000-year-old engineering wonder hides beneath an Italian town.

This cathedral hides a sculpted dog that determines your fate and an unexploded shell from World War II.