After a nearly successful attempt on Hitler's life, the conspirators met their fate in the courtyard of this Berlin building.

Floating swimming pool within a moored vessel.

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

Germany's Glienicke Bridge has a shady history of clandestine meetings, espionage, and spycraft.

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

An 18-mile-long tunnel for sewage waste will soon wind within the bowels of Washington, D.C.

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

The fire inside this temple has burned for more than 1,500 years.

A slice of central Asia in the middle of Berlin.

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

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

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

Tiny memorials honor individual victims of the Holocaust.

One of the world's heaviest musical instruments towers within a popular urban park.

A towering monument to war, located on a beautifully peaceful hill.

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

Berliners converted a bombed-out, disused lot into a community-run urban farm with its own cafe and bar.

This striking royal residence is the largest Renaissance-style castle in Scandinavia.

When this Iron Age bog body was discovered in 1835, it was thought that she had died recently.

The art museum is decorated with creatively remodeled pre-Nazi swastikas.

Climb to the top of its spiral spire for spectacular views of Copenhagen.

Copenhagen's celebrated theme park and gardens.

Water-powered gadgets whirr to life in this quirky eco park.

Tubing through a cave lit with glowworms is a magical underground experience.