A reportedly haunted parking structure with alleged links to Jack The Ripper.

The oldest private residence in New York City.

An interesting look into 18th-century American history.

This massive subterranean fissure is known as the "underground Grand Canyon."

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

A stately castle in the northern Italian countryside has been restored after years of neglect.

Once a training ground for Olympic athletes, this artificial ski slope has fallen into ruin after a fire in 2012.

A geological wonder shrouded in myth.

This 20th-century replica of a 13th-century castle has itself fallen into ruin.

This fortified L-shaped tower is the ancient seat of clan Hannay.

A railroad tunnel that, upon its completion, was considered one of the engineering marvels of the modern world.

Giant busts of 42 U.S. presidents are sitting in a field in Virginia.

A mixture of strange symbols, ciphers, words and cryptograms carved in 1876 remain unsolved to this day.

One was an astronomer who spent his life chasing solar eclipses, the other helped make Emily Dickinson famous.

In the middle of a New England forest sit the crumbling ruins of World War II-era ammunition storage bunkers.

A 2017 crowdfunding campaign saved this historic castle from being destroyed.

Enjoy dishes that founding fathers once ate at this Colonial Williamsburg pub.

This massive piece of aviation history calls this residential neighborhood home.

Hiding in plane sight.

A boulder in the Churchyard of Down Cathedral marks the legendary burial place of "The Apostle of Ireland."

Every equinox this Maya pyramid puts on a spooky ancient light show.

Oddly enough, a pair of Wolfs funded the construction of this Little Red Riding Hood sculpture.

This is the oldest Roman-made bridge in the city still existing in its original state.

This fancifully decorated Victorian home in New York’s Hudson Valley is the only known fully domed octagonal residence in the United States.