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

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

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.

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

The 72-foot giant escaped confinement in a large patch of mulch only to be reburied in the sandy shores of the Potomac River.

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

It was once the base for a series of domestic terror attacks.

There's a crumbling old mansion inside the Smithsonian National Zoo.

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

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

Washington's iconic carousel has a nice piece of Civil Rights history.

Home to items never before seen by the public.

The narrowest house in America is seven feet of pure spite.

The oldest continuously operating fish market in the United States.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

The romance of early commercial flight still fills this Art Deco destination.

This small island off the coast of Uruguay hosts the largest colony of sea lions and fur seals in the southern hemisphere.