Upside-down trees serve as natural flower pots in this hanging garden of Alaska.

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

This advertisement for talcum powder was painted on the rock face and has since defied removal.

A state park that once served as an important river crossing, and now offers protected lands for endangered plants and animals.

Remnants of a storybook amusement park hidden behind a strip mall.

The 320-year-old tree that greeted General Lafayette and rerouted an interstate highway.

Walk through the history of American pop culture.

An unusual sculpture, an interesting history, in a strange place, for a good cause.

FDR's Art Deco hospital tower was hopelessly inefficient.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

The wooded estate of the Forest Service employee responsible for D.C.’s cherry blossom trees.

The bridge's highly-contested plaque (once again) honors Confederate President Jefferson Davis.

This historic lighthouse was well known for the large number of women who served as its keeper.

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

The world's oldest continuously operating airport was founded by the Wright Brothers.

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

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

A benevolent, 16-foot-tall river dragon lives on a suburban lawn.

This 1830s store is believed to be the site of Harriet Tubman's first stand.

A star fort along the C&O Canal in western Maryland that protected America in three wars.

Electronic inventions that resulted in products and systems we use every day are on display in this labor-of-love museum.

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

This one-room cabin where the young colonel slept during the French and Indian War.

One of the oldest anatomical theaters in the U.S. still in use was once the site of an infamous cadaver riot.