Hide from the tourist hordes in these relatively unknown, and unguarded lava caves.

Earth's tallest volcano is sacred to Native Hawaiians, and home to a dozen world-class observatories.

Take shelter from Hawai'i's tropical heat under the massive canopy of largest Banyan tree on the island.

The only royal palace on U.S. soil has been a territorial capitol, a military headquarters, and a prison for a queen.

The Vermont square that inspired Shirley Jackson's "The Lottery."

A classic roadside attraction on Vermont's historic Route 5.

These mysterious petroglyphs in Vermont reflect a troubled history in the treatment of Native American culture.

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

Look closely and you’ll notice that the color changes a third of the way up the tower.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

Was there a small "backpack nuke" hidden in the attic? JFK apparently thought so.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

Washington's iconic carousel has a nice piece of Civil Rights history.

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

Home to items never before seen by the public.