Rolling sand dunes of the Sahara... in the middle of the Atlantic Ocean.

The old ceramics factory on Boa Vista shows the power drifting sand has to destroy buildings.

This curious sculpture represents the perseverance needed to take to the skies.

A century-old shot ball factory tower is open to the public once a year.

This monumental work of art symbolizes the coming together of a previously divided city.

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

A prime example of socialist modernist architecture, wrapped in a enormous fresco about the media.

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

A small hippo-shaped fountain in Berlin, Germany.

A statue of an astronomer gazes at the sky as a tribute to Caroline Herschel.

A memorial in the Tiergarten is a reminder of the suffering inflicted on homosexuals by the Nazi regime.

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

A monument to the man who almost killed Hitler.

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

This monument depicts a harrowing event involving an escaped polar bear.

A pair of mosaics marks the spot where the last accused witch of Dundee was put to death.

The rotting skeleton of a shoreside fun fair that was destroyed by fire and storms still haunts the Brighton ocean view.

The commemorative stone column conceals a secret laboratory.

Legend says this mysterious stone head belongs to a woman who was petrified by an alchemist.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

Memorials at a Florence railway station remember the citizens who were deported from Italy and sent to extermination camps.

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

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

The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.