These experimental weapons brought World War II to Nebraska as well as 26 other U.S. states.

This modernist building is the last remnant of an ambitious plan to restore a neighborhood.

The crumbling remains of a 19th-century textile factory.

This fairytale inspired, warped building houses restaurants, shops, and a radio station.

This Communist-era residential block is one of the longest residential building in Europe.

The site of the first battle of World War II.

A haunting deserted hotel is a favorite with artists and photographers.

A mysterious structure left behind on the Polish mountainside, sometimes called "Hitler's Stonehenge".

This sprawling concrete suburb of Kraków was designed by the Soviet Union as the model proletarian city.

A peculiar family mausoleum built by a German nobleman captivated by the occult.

A menacing statue of this mythical creature can be seen at the legendary site of the monster's lair.

This hidden collection of everyday objects illustrates life within communist Poland.

A national collection of Communist-era musical posters.

A fairytale Gothic castle steeped in Nazi treasure conspiracy theories.

This Nazi ruin was the site where Hitler was almost blown up by a suitcase bomb.

Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

Countless stories attempt to explain Poland's mysterious J-shaped trees.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

This open-air museum was originally a World War II testing ground for German missiles and rockets.

A memorial to a Swedish hockey player's "encounter" with aliens.

A monument to Poland's famous alleged UFO abduction case.

A regular looking rock with an unbelievable history.

The scene of the United Kingdom's most famous UFO incident, dubbed the "British Roswell."

This spacecraft-shaped water tower is only a part of the mysterious UFO mania in this Brazilian town.