Giant acorn-shaped 19th century gazebo from which suburban Washingtonians gazed upon the original "silver" spring.

Baltimore's classic clock tower was once topped by a rotating, 20-ton medicine bottle.

Once America's tallest structure, now a Baltimore landmark.

The whole world in one water tank.

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

Easter in Westminster may be the only time and place to behold Edgar Allen Poe made entirely of Marshmallow Peeps.

The final resting place of the tragic king and queen of the Jazz Age is tucked away in a small Maryland graveyard.

This scenic Maryland park was the site of one of the worst prison camps of the Civil War.

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

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

This bug-eyed water wheel uses the power of the Sun to clean up Baltimore Harbor.

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

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

The ruins of this long-abandoned unsuccessful gold mine can still be found.

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

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

Bizarre Cavern.

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

A museum dedicated to exhibiting remarkable outsider art.

This train station inspired the name of a 1970's rock band and provided the backdrop for their album cover.

These unusual rooms on wheels are holdovers from the 1960s.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

The romance of early commercial flight still fills this Art Deco destination.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.