This massive swimming pool is the high tech home to the human-powered submarine races.

A swimming hole in the historic industrial quarry that supplied the marble for the Baltimore Washington Monument.

This golfball sized platinum iridium cylinder is the official starting point for all national weight calibrations

A remote horde of architectural treasures fit for Indiana Jones.

This English-inspired Maryland garden is home to acres of opulent plant life including bushes shaped into an entire fox hunt.

A local farm's collection of unusual structures from a now defunct storybook amusement park.

An eerie, decaying ghost town destined to fade into the forest.

Bizarre Cavern.

This free, take-a-book shop seems like a trick but isn't.

This extraordinary Depression-era expenditure was modeled after a postcard of a Mediterranean hotel.

A living maritime paradox still floats in the same lake where it was built and resurrected... or was it?

Could it have picked a better place to land?

This dramatic rail curve was once the target of a failed Nazi attack.

The graffitied ruins stand hidden within the Pennsylvania woods.

The origin of this mechanical boy was a mystery until he revealed his maker by writing it in perfect cursive.