A whimsical village of unique treehouses resides in a Washington forest.

Once a year, at exactly 11:11 a.m., this monument comes to life.

A geological mystery on Camelback Mountain.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

This Virginia railway overpass is said to be haunted by a serial killer in a rabbit costume.

A ship that lived many lives under many names is now known merely as the "Ghost Ship."

The entrance to this sinisterly named tunnel hides behind a Tim Hortons.

The world's first aircraft factory has been hiding inside an automobile plant for almost 80 years.

This otherwise ordinary close on the Royal Mile constituted the end of the world for Edinburgh’s poorest residents.

The world’s first museum dedicated to the history of childhood opened in Edinburgh in 1955.

Experience what life was like in Ireland during the Viking and medieval ages.

Hidden on two floors of downtown building, the library has an incredible deal on rent.

Trek into the depths of the cave where 17,000-year-old paintings exist alongside 400-year-old graffiti.

Louisa May Alcott based “Little Women” on her experiences growing up in this house with her sisters.

Located just behind a quiet residential neighborhood, this is ground zero for the Salem witchcraft hysteria of 1692.

The first permanent memorial to a unique secret weapon of World War II.

Exact replica of the ancient monument, but much, much lighter.

Volcanic stone sentinels stand watch at a Korean Bell Garden in Virginia.

This network of narrow, medieval passages has the most delightful name.

The final resting place of the tragic king and queen of the Jazz Age is tucked away in a small Maryland graveyard.

These abandoned waterworks are crumbling into the Potomac River.

The hidden offices underneath Memorial Bridge have been locked up since 1976.

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

It was once the base for a series of domestic terror attacks.