Stand at the point where the two mightiest rivers in the United States converge.

One of the last few period-correct, hand-operated canal locks in the country.

A short boardwalk through a swamp leads to the spot from which the Louisiana Purchase was surveyed.

A devilishly named gorge that was a sign of salvation for many pioneers.

This little brick tunnel built by Confederate forces was used to conduct surprise attacks on the railroad.

This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

The final resting place of an unidentified revolutionary soldier sits behind a Virginia church.

A massive, majestic mammal watches over pedestrians from his perch atop a former B.P.O.E. lodge.

An original apothecary from 1792.

This small pedestal marks the spot of the first lot of land sold in Alexandria, Virginia in 1749.

This colonial tavern played host to George Washington, Thomas Jefferson, and other famous early Americans.

Long buried under the 20th-century landscape, this lift lock of the Alexandria Canal is the lone remnant of an ambitious early American transportation project.

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

This Masonic lodge was the first major private building to be constructed in Washington, D.C. after the Civil War.

Obscure Freemasons still live in D.C.’s largest private residence.

The world’s largest Masonic temple was saved by the White Stripes.

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

This cannon dating to 1755 has stood guard at this suburban intersection since 1915.

A renowned Civil War veteran, this Bald eagle now presides over the Wisconsin State Assembly.

For the last eight decades, this curious shop has been ridding Atlanta of bad juju.

One of corporate America's best-kept secrets is also one of the most publicly displayed.

A museum in Mississippi celebrates the history of Coca-Cola and the man who brought it to the masses.

The ill-fated plan to reroute the Mississippi so that Union ships could bypass Confederate fortifications on the river bend.

This iron and wood Civil War city-ship was the first vessel to be sunk by an electrically detonated torpedo.