A relic of FDR's brief foray into utopian urban planning.

Four bald cypress trees in Lafayette Square, across from the White House, mark the southern edge of a 100,000 year old cypress swamp.

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.

Corn-inthian columns with a uniquely American take on neoclassical architecture.

The 28,000-year-old specimen is remarkably intact.

A B-17 bomber stands as a memorial to the residents of Tulare County who served in World War II.

A 19th-century cabin built into a hollowed-out Sequoia tree.

Quite simply the largest tree in the world (by volume).

Four hundred granite steps were built into this massive rock by the National Park Service.

A whimsical tower with a spiral staircase, inspired by the Space Age and the Möbius strip.

The fifth tallest statue in the United States is a shirtless monument to the oil worker.

One of the best examples of Art Deco architecture in the United States.

An acoustic anomaly with a mysterious cause.

A half-size replica of the World Trade Center towers above Tulsa.

A mysterious and terrifying public art goblin seemingly meant to inspire local legend.

The grandson of a Kiowa chief created what has become the iconic symbol of a city on the Plains.

A larger-than-life monument to the overlooked women who braved Western expansion and broke down societal barriers.

At 207 feet, one of the world's longest continuous escalators.

America's first federal monument.

This simple stone memorial remembers a secret, Geneva Convention-defying interrogation base from WWII.

The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.