Formerly Yugoslavia's "forbidden island," this sleepy little city still holds the abandoned remains of military strongholds.

This truly palatial work of Communist-era architecture now sits crumbling on a Croatian beach.

The rusted creatures wait to be discovered in Prague's botanical garden.

Mummified monks and the accidentally interred, in a 17th-century crypt.

Europe's second largest ossuary wasn't discovered until 2001.

Of all the houses that grace this neighborhood, only one is a testament to surreal architecture.

This former insane asylum now holds a pathological anatomy museum.

Swarovski's museum/theme park is a fake diamond fantasia overlooked by a giant.

This skeleton-filled altar piece served as a backdrop to one of the most iconic scenes in "The Sound of Music."

The personal charnel house of Anton Bruckner.

The shell of a medieval fortress offers commanding views of the area it once protected.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

Vienna's underworld of tunnels and subterranean rivers made an iconic appearance in a 1949 Orson Welles film.

An abandoned Jewish sanatorium is tucked within the woods of Poland.

One of the largest barracks of the Austro-Hungarian monarchy's military is now an abandoned ruin.

Hungarian mummies in beautiful painted coffins.

The ruins of an abandoned crematorium haunt an eerie deserted German cemetery.

Retirement home for giant obsolete machines.

A peculiar trapezoidal building covered with wonderful humorous reliefs.

The industrial monstrosity known as Bagger 258 is a colossal mining machine built in the DDR - but now left for dead in a German field.

This fresco-covered medieval monastery hangs from the side of a steep cliff.

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

This riverside restaurant has been serving customers since 1146.

A German apartment building hosting as many trees as human occupants.