A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

Golden and naked, the figure that was once the highest point in New York is all that remains of the second Madison Square Garden.

Yo, Adrian!

The origin of this mechanical boy was a mystery until he revealed his maker by writing it in perfect cursive.

A daily replay of the experiment that proved the rotation of the Earth.

This strange, big-tailed beast became a Pennsylvania town's unofficial mascot.

This Delaware River bridge is emblazoned with a catty slogan from a more prosperous time.

This giant disembodied horse head seems to balance impossibly on its nose.

Eccentric concrete mansion and museum designed and built by hand from the inside out.

Mysterious rocks that ring musically when struck.

The solitary grave of a schooner captain killed by lightning while serving biscuits.

The land is home to swimming ponies and a legendary 18th-century treasure.

The world's longest known cave system.

The Dover International Speedway is home to a towering, concrete-skinned, racecar-hungry behemoth.

America's oldest archaeological site or a muddled case of wishful thinking.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

Northern Ireland's Brobdingnagian stepping stones.

A mysterious echo seems to defy the laws of acoustics.

This ancient Irish tower could easily have stood in for Rapunzel's prison.

The ancient tomb acts as a calendar that keeps perfect time.

World War II bunker still standing on the New Jersey beach.

American involvement in World War I officially ended in 1921 in New Jersey, three years late and thousands of miles from the battlefield.

This museum explores the grim reality of life in the earliest British colonies in America.