This war hero's old shop remembers the fine line between medicine and quackery during the Revolutionary War.

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

Exact replica of the ancient monument, but much, much lighter.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

A former major munitions plant that has been converted into a sprawling art space.

The Kirkland Monument remembers a selfless Civil War hero who braved the battlefield to give water to his dying enemies.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.

This historic mansion was built as a symbol of love between a husband and wife.

This 29-ton granite ball spins around at the slightest touch thanks to a scientific phenomenon.

One of the only Florida forts to remain in the hands of the Union all through the Civil War still stands as a historic stronghold.