The walls of the iconic dome are hollow and have a secret stairway.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

This statue of the "father of television" stands prominently in the United States Capitol.

Washington D.C.'s most famous pianist, composer, and bandleader still tickles the ivories outside Howard Theater.

An amazing example of early-20th-century architecture, this church features marble transported from Utah.

A tribute to the pop culture icon overlooks this Washington D.C. intersection.

Centuries-old columns from French monasteries provide structure for this courtyard within an Ohio art museum.

Inside an airport, visitors can explore this museum where history takes flight.

This unique collection collects pieces of art etched into thin pieces of stone.

At Chicago's revered Field Museum, visitors are invited to learn about and literally explore DNA.

A lush green oasis in the middle of Chicago.

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

This Hawaiian cattle ranch acts as a museum devoted to the island cowboys that predate the wild west.

A magnificent waterfall nestled in the heart of the El Yunque National Forest.

A graceful natural rock formation stands astride the point where the Gulf of California meets the Pacific Ocean.

This life-sized effigy commemorates the dedicated abolitionist and social reformer.

Inside the Wayne County airport is an amazing collection of lights and sounds.

World's largest Christmas store.

These dramatic cola-colored falls have appeared in a poem by Henry Wadsworth Longfellow and a song by Sufjan Stevens.

Two dozen rescued bears roam (mostly) free at the largest bear ranch in the U.S.

This shallow cave got its name from copious amount of human bones found inside.

Island where motor vehicles are banned -- home to the only carless highway in the United States.

The fifth-longest suspension bridge the world, connecting one Michigan peninsula to another.