No need to strap in for a "ride" on this walkable roller coaster.

A long spiraling walkway winds through the woods, and around a copper beech tree at the center.

A unique Holocaust memorial tells the personal stories of the Jewish residents exiled from greater Berlin.

This historic stone bridge has an entire neighborhood clinging to its sides.

A stairway to heaven, or to nowhere at all.

When the rain falls, this drain system turns into a musical instrument.

Soaring over 6,000 feet in the Bavarian Alps, this beer garden was once Hitler's 50th birthday present.

This "floating railway" is one of the world's oldest monorail systems.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

The giant metal fruit was once the symbol of a large farm.

Fortifications built for a Soviet invasion that never came now sit abandoned in a losing battle against nature.

A schooner, nicknamed "The Unsinkable," with a long history of survival in the Indian Ocean.

This abandoned villa of makeshift buildings was once the home of dancer Elis Sinistö.

Not far from a popular beach, an unfinished, abandoned mansion for Bulgaria's last communist dictator.

The beehive-like buildings of this abandoned resort reside near the border of Mauritania and Senegal.

Once the central jail for Los Angeles, this building housed inmates like Al Capone, those arrested from the Zoot Suit and Watts Riots, and individuals imprisoned for their sexuality.

An abandoned observatory in the middle of the Illinois prairie.

The only residents of this abandoned housing development full of identical castles are stray cats and dogs.

A small strip of artistic displays is tucked away in a flea market.

Two men built this castle on the Florida coast as an artistic “landscape sculpture.”