Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

This Great Depression-era creation was once known as the strangest house in the world.

Along the Palisades skyline are the ruins of a large mansion built in 1911 and demolished in the 1930s.

Whimsical artist house in the New Jersey woods.

The remains of a 19th century spring, and the site of an infamous unsolved murder.

The site of one of history's most indelible and horrific tragedies.

The remains of a century-old mansion that met a fiery demise years after it was deserted.

These mystical miniature houses bring a touch of magic to the New Jersey woods.

Once in a state of dilapidation, this candy-inspired fortress is now being revived.

This renaissance château was home to an infamous witch hunter who sent a hundred suspected witches to their deaths.

The 14th-century ruins are said to contain healing powers.

Underneath the city that invented pilsners are a series of historic tunnels that have been storing beer for centuries.

The mystery of the Putim Ossuary involves a tricorn hat.

This network of conjoined cellars was riddled with traps and supposedly allowed the townspeople to pretend their homes were deserted.

These 17th-century mummies are no longer naturally preserved, but remain on display today.

A former squatter's paradise outside Prague.

Mysterious painted skulls in Moravia.

Enormous sandstone towers loom within a Czech forest.

Folklore says this medieval fortress was plopped atop a portal to hell to trap the demons below.

The deepest sinkhole in Central Europe comes with a grisly tale and an unusual nickname: “The Stepmother Abyss.”

A museum of alchemy and a basement laboratory all housed in an ancient building in a Gothic tower.

A collection of anatomical samples from one of the first anthropologists to suggest that humans reached North America by crossing the Bering Strait.

The risqué mixed-media sculptures are supposedly a metaphor for Czech politics.

The hidden lair of an alchemist rediscovered in a 2002 flood.