Time travel with sweets across history at this research-based candy store.

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

The only recreation of William Shakespeare's indoor playhouse.

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

The semi-reclaimed ruins of this canal were once part of an ambitious plan to reroute the mighty potomac.

Outsider art meets paleontology at this roadside reptile repository.

This pre-Revolutionary War grist mill ground corn and flour for soldiers in seven American wars.

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

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

Outdoor exhibits explore the contributions of European, African, and indigenous peoples to American frontier culture.

This former Cold War missile control site played an important role in the creation of GPS.

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

Captain John Smith thought these cliffs were amazing in 1608 but sharks thought so 20 million years before him.

The design of this historic domed church was influenced by Thomas Jefferson and intended as a statement of religious freedom.

The world's oldest continuously operating airport was founded by the Wright Brothers.

A swimming hole in the historic industrial quarry that supplied the marble for the Baltimore Washington Monument.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

The childhood home of the Sultan of Swat is just a line drive away from Oriole Park at Camden Yards.

This advertisement for talcum powder was painted on the rock face and has since defied removal.

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

A portal into the bricked up canal that runs through the heart of Washington D.C.

The only National Monument ever to go missing for nearly 50 years then resurface in a dump.

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.

The national park was once a plantation estate.