A Norwegian-born sculptor created these soaring guardian angels at the entrance to Hoover Dam.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

An enigmatic modern marker left next to a historic Roman site.

The world's largest fire hydrant is supposedly tornado-proof.

Henry VIII's forgotten castle was built by the gunpowder-obsessed king to be defended solely by cannons.

An artistic tribute to the famous singer, just around the corner from where he was born.

The Pope’s secret escape route.

A hidden treasure of an abandoned city lies deep in the jungles of Campeche, Mexico.

This smaller cousin of the Forbidden City has gone from ancestral sacrifice to tourist's whispers.

A Masterpiece with a Tragic History.

There are lots of hands and feet stamped in the cement in front of Grauman’s Chinese Theater, but Mel left behind something extra.

A visionary, futuristic sculpture in Los Angeles that never met its extraterrestrial potential.

A beautiful geyser under environmental threat.

This geothermal hot spring hides beneath a slowly growing mineral dome.

A contemporary art installation housed within a Gothic cathedral.

A sweet symbol marks the place where torturous executions were once carried out.

The fountain marks the area where hundreds of accused witches were burned at the stake.

The final resting place of soldiers' loyal canine companions.

A six-ton wedding present for the King of the Scots.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

Ship-sized kinetic sculptural fantasy.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

London's amazing modernist public square that never was.