An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

Washington's iconic carousel has a nice piece of Civil Rights history.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

Look closely and you’ll notice that the color changes a third of the way up the tower.

A museum and tribute to a brave profession.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

Sitting atop San Francisco's tallest hill, a cross honors the victims of the Armenian genocide.

Inspired by Thomas Stothard's painting of the "Journey to Canterbury," albeit with Canterbury natives.

The fossilized remains of ancient California redwoods.

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

These four islands right offshore have waterfalls, colorful lights, fancy buildings, and a secret purpose.

A famous big wave from Japan serves as a tribute to the victims of the disastrous Elbe flood.

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

Cold war icon and onetime "hole" in the iron curtain.

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

Berlin's beloved bear is immortalized at the Museum für Naturkunde.

Berlin's natural history museum houses the world's largest mounted dinosaur and the late beloved polar bear Knut.

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

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

A labyrinth hides in plain sight at each of the city's 270 Tube stations.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

This skewed English house has looked like it's going to fall over for centuries.