This otherwise ordinary close on the Royal Mile constituted the end of the world for Edinburgh’s poorest residents.

A labyrinthine network of chambers with a storied past hides below Edinburgh's South Bridge.

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

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

An underground city of salt.

The former Nazi Germany concentration camp stands as a museum to remember this dark chapter in European history.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

Model Trains and Much More in Hamburg.

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

Single runway interrupted by a busy road that cuts across its middle.

An effigy of a trapped paratrooper dangles from a Normandy church to commemorate one remarkable D-Day event.

Bloodstains can still be seen in this medieval church where two medics saved lives on D-Day.

A memorial to the nearly 10,000 American soldiers laid to rest on the beaches of Normandy during WWII.

This enormous "cloth of the conquest" depicts the Norman invasion of England in mind-blowing detail.

The largest greenhouse in the world is home to over one million types of plants.

This crumbling coast and its teetering tower are literally filled with history, but they are also at great risk of becoming history themselves.

This ancient Egyptian obelisk still bears the wounds of World War I.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

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

Collection dedicated to brands, packaging and advertising.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Scattered throughout London are ancient remnants of the city's former bounding wall.

Eighty million natural history specimens call this gargantuan museum home.

One part local history, 99 parts gruesome haunted house.