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

A rare tour of an aristocrat's private home reveals valuable 17th-century paintings from artists like Rembrandt.

A beautifully eclectic mix of architectural styles.

A beer pipeline runs beneath Bruges.

Christ's blood allegedly preserved in a Belgian town.

This narrow Ghent alleyway is an officially sanctioned street art tunnel.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

A Museum of Psychiatry in a still-operating mental institution.

Leaf through over 30,000 artists' sketchbooks in what may be the world's largest collection of doodles

Rummage through this sunken ship, but leave your scuba gear at home.

A former insane asylum despised by Nelly Bly and Charles Dickens is now fashionable apartments.

Named the fifth most beautiful building in America in 1885, this former courthouse boasts the best view in the Village.

A bit of retro transportation flair preserved in the world's largest department store.

The New York hotel where tragic visionary Nikola Tesla spent his final hours, destitute and alone but for the pigeons.

This hidden library of physiological ephemera contains centuries worth of knowledge on the vim and viscera of the human body.

The beautiful tunnel that ran from the lobby to Penn Station is still hidden underneath 34th Street.

Lie in a hammock where George Washington stood.

The world’s oldest and biggest bookstore stocking only mystery, crime fiction, espionage, and thrillers.

This little museum is built on a theater that was once a wildly elaborate speakeasy.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

Elevated freight railway turned wildly successful urban park.

A crumbling hospital from the 1850s on Roosevelt Island.

One of only two commuter aerial tramways in the United States.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.