The whole world in one water tank.

This beautiful stone arch bridge wasn't even expected to stand for one day, but people have been crossing it for centuries.

The design of this historic domed church was influenced by Thomas Jefferson and intended as a statement of religious freedom.

A labor of love built by local hang-gliding enthusiasts, this ideal launch spot was outlawed by the authorities and has since been largely abandoned.

A remote horde of architectural treasures fit for Indiana Jones.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

A pre-Industrial Age iron furnace and the site of a nearly-forgotten piece of Black history.

Live data is transmitted from the Atlantic coast to instantly recreate the ocean waves in this fountain at the NOAA headquarters.

Built by the patriotic residents of Boonsboro in a single day.

This abandoned sea fort has become an accidental bird sanctuary.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

Captain John Smith thought these cliffs were amazing in 1608 but sharks thought so 20 million years before him.

After hundreds of years of settlement, this once-bustling fishing village sunk into the Chesapeake Bay.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

This Maryland farm is known for its amazing corn mazes and its 30-foot junkbots.

A girls' boarding school inspired by the Chicago World's Fair, once abandoned, now restored to strange and scenic glory.

An intricately designed junk art house with four extravagant junk art cars hidden in the suburbs.

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

A hidden alley in urban Baltimore is a haven for graffiti artists.

This beloved Baltimore spot features caged dolls, a giant Pez collection, and many, many mannequins.

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

The land is home to swimming ponies and a legendary 18th-century treasure.

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

Bizarre Cavern.