This volcanic plug boasts the longest recorded history of any Scottish stronghold.

A historic Black graveyard hidden in the parking lot of one of America's largest malls.

The final resting place of one of Thomas Jefferson's formerly enslaved sons.

During the American Revolution, this mansion hosted failed peace talks between the British and Americans.

A retired subway car stands alone in a field in the middle of Queens.

Giant busts of 42 U.S. presidents sit, crumbling in a field in Virginia.

Heron, whitewater rapids, and urban industrialism all add to the beauty of this concrete nature walk.

A small Richmond island dotted with the remnants of hundreds of years of history.

Under a playground is a little-known sealed train tunnel that likely contains the bodies of workers trapped by cave-ins.

The largest collection of historic military firearms in the United States.

This hidden gem reveals the history of Britain's first police force.

A burial ground of rusting metal grave markers.

The farthest northwesterly point of the British mainland is one of the most remote places in the Scottish Highlands.

No one knows who painted this mysterious mural in a Penn State basement.

A secret door leads to this cozy dive that sells only “milk.”

The retired vessel is South America's first floating museum.

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

This museum explores the grim reality of life in the earliest British colonies in America.

A large boulder marks the place where the island of Manhattan was purportedly "sold" to the Dutch.

Instead of using billboards, some people here relay their messages on the side of a mountain.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

This spooky statue sits outside a famous Prague theater.

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