Lucerne's central prison was converted into a tourist hotel with a bare minimum of changes.

Achill's most recently abandoned village dates back to to the Age of Enlightenment.

One of Ireland's most infamous prisons for rebels including men, women and children.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

The Argonaute submarine was the French navy's pride and joy in the 1950's.

World's only telecommunication tower with a wooden pinnacle.

This church, buried halfway in lava rock, is all that remains of a Mexican village destroyed by a volcano.

A mysterious monument meant to be a guide into "an Age of Reason" was destroyed after an apparent bombing.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

This legendary stone is of unknown origin, and throughout history has been a literal touchstone for British leaders.

Supposedly Satanic numbers adorn this preserved submarine sail.

A perfectly circular stronghold constructed in the 10th century is now a nucleus of Viking culture housing a museum, village, and reenactment of an epic Viking battle.

Relics of Australia's convict past, and a modern scene of unimaginable horror.

Deadly airliner crash preserved for those willing to climb and pay respects.

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

Pompeii's less famous neighbor is still revealing her secrets.

Rivers of cattle blood gone, a strange Escheresque building remains, the last of its kind.

Giant statue of a disembodied head.

Abstract dinosaur models in London.

A monument celebrating the idea of reaching inaccessible places.

Huge winged monument in the United Kingdom.

Louise Bourgeois' 30-foot-tall steel spider sculpture.

Home to secret Eastern Bloc spy equipment and the largest stretch of the original Berlin Wall outside of Germany.

Some of the tallest ancient American ruins continue to inspire awe and curiosity.