This elegant arc of a waterfall marks a religious turning point.

Iceland's "Smoky Valley" is a beautiful river that is shrouded in a constant cover of steam clouds.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

Iceland's largest lagoon is home to stunning multi-colored icebergs.

This fantastical waterfall is hidden in a cave located in a cracked cliff.

Rising from the sea like a stone monster.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

Medicinal spa created with the discharge from a geothermal energy plant.

Bursting forth from a historic German neighborhood, these day-glo palaces are now a bright fixture in the town.

The prototype for all Nazi concentration camps.

A discreet little stairway on St. Nicholas Avenue leads to a quaint and unexpected cobblestone street of 19th century wooden rowhouses.

Just your average Marie Antoinette–themed speakeasy in an abandoned 19th-century subway tunnel.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.

A Bed-Stuy gymnasium that hosts expansive raves, performances, dance parties, and more.

A veritable variety of odds and ends.

Down a stairway in the East Village, you could once read a plaque describing an alternate history of a fictional version of Manhattan.

Tucked in the back of this amazing antique store is an important piece of medical history.

The haunting, dilapidated remains of a former poorhouse on Staten Island's Greenbelt.

A riverfront park that both remediated and preserved its industrial past.

Imagine having a street run right through your home, or better yet, a historic bridge three stories high.

Haven for steampunks.

This small, hidden cove is home to abandoned boats.

This interactive gallery makes you feel like you've stepped into a fantasy world filled with whimsical monsters.

A Victorian cemetery in the heart of Brooklyn remains a popular mecca of morbid curiosity.