Moscow's imposing monument to the Space Age.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

The famous author's cottage hideaway.

New York City's smallest piece of private property.

Sweden's first nuclear reactor, R1, can be visited 25 meters underground.

This quiet, unassuming spot in Budapest was the birthplace of the bloody 1956 Hungarian Revolution.

A marvel of technology a century ago, this disused power station now offers a lovely glimpse into the industrial design of the past.

This quaint Hungarian railway system is operated exclusively by children between the ages of 10 and 14.

Budapest's Communist-era statues, banished to the suburbs.

An abandoned village that doubled as "The Hunger Games"' post-apocalyptic wasteland is up for grabs.

The cruel trial of a 13-year-old boy inspired the creation of this now abandoned reformatory.

The first statue of Christ sleeping on a bench in the United States confused its affluent parish.

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

The rocks in this arid basin leave trails of movement behind them.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

For two weeks every June, fireflies in the Smoky Mountains perform an astonishing light show.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

The fairy tale castle of the "fairy-tale king."

Bowl in splendor, if you're lucky.

This abandoned lighthouse looks like a rusting oil rig, but has managed to survive a number of storms.

This sprawling museum holds one man's giant collection of real tanks.

The abandoned "Red Star Train Graveyard" is the final rusting place for precious artifacts of train history.