Ancient human, animal, and geometric figures drawn in the earth.

A once grand hotel is being retaken by the wilderness it once capitalized on.

The sculpture is made of more than 100,000 knives collected to raise awareness about violence.

The remains of Crystal Palace Great Exhibition of 1851.

These mouldering mansion ruins remember a time when the Catskills were nothing but luxury.

The walkable ruins of an 19th century hotel, destroyed in a horse cremation gone wrong.

This abandoned Poconos resort is haunted by a history of kitschy romance and a violent fugitive.

An abandoned hotel in the highlands of Bali is shrouded in stories of ghosts, curses, and corruption.

This twice-relocated "Usonian" home is among the smallest built by master architect Frank Lloyd Wright.

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

This innocent-looking townhome is actually a subway exit.

Obscure Freemasons still live in D.C.’s largest private residence.

An Industrial Revolution-era public work that purified water using nothing but sand.

One lonely, modern pyramid has gone from corporate think tank to deserted boondoggle.

This trail follows unique stone railroad tracks and a historic waterway to the south coast of Devon.

This harsh mountain path was built as a strange attempt to improve the health of Turkmen citizens.

There are two legends behind the origin of this unusually tall sanitary structure.

A cake-themed art installation tucked away in historic Chinatown.

An engineering error ensured this cavernous 350-foot-long subterranean thoroughfare was never used as intended.

This 13th-century monastery chiseled into the side of a mountain is equipped with a bridge that can be lifted to protect against raids.

The hidden offices underneath Memorial Bridge have been locked up since 1976.

A remnant of the last Ice Age, this lake is surrounded by fascinating rock formations.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

It was an experiment to prove that glacial boulders and rocks can be used in constructions and dwelling.