The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

Locals transformed this Canadian evergreen into a secret hangout with spectacular views of Vancouver's skyline.

Shoreline strewn with the remains of ghostly fallen trees.

A Roman-style column in Oregon hides a spiral staircase inside.

This gorgeous beach hides behind two headlands in Oregon's Ecola State Park.

Mountain known by the Tillamook Tribe as "the place of the supreme deity."

This unassuming cheese empire in rural Oregon churns out more than 150,000 pounds of cheese each day.

Two massive rock outcroppings on the Oregon coastline.

Only known mainland rookery of the threatened Stellar sea lion.

The park preserves a single, rare species of carnivorous plant that spells doom for unsuspecting insects.

On the Oregon coast is a natural hole that seems to be draining the sea.

There's something big lurking beneath the surface of this tiny Oregon park.

The artwork commemorates the many ways 20th-century people perished while on the clock.

A fence constructed completely of skis on Monroe Street.

A bronze statue on a downtown corner honors Minneapolis's favorite career gal.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

Disks are rolled out onto the south lawn to absorb the impact of Marine One's wheels like giant coffee coasters.

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

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

A historic arena where the Beatles played their first concert in the U.S.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

Largest Roman Catholic church in North America.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.