Chicago's Navy Pier on Lake Michigan was a training hub for aircraft carrier pilots during WWII.

This surprising gem is a world-class archeological museum hidden at the University of Chicago.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

The site of a concentration camp where inmates were made to take part in one of the largest counterfeiting operations in history is now hauntingly empty.

The "Prussian Versailles" that is as glorious today as when it was built.

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

This World War II bunker now survives as a documentation of the Nazi regime and war crimes.

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

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

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

The most visited, and possibly most controversial, museum in Germany.

This $3 million model train takes you through Chicago, Seattle, and the thousands of miles in between.

The highest point in Washington state is a volcano covered in glaciers.

The only Bahá'í house of worship in North America and one of only a handful worldwide.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

Wall Street has a new heroine, a bronze statue of a small but fierce girl.

Quite simply the largest tree in the world (by volume).

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

The world's longest known cave system.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.