Spectacular mineral formations fill these caves, which have been used for everything from smoking meat to stashing illicit liquor.

The only surviving 19th-century water-powered mill found in the Washington, D.C. area.

Perhaps the most scandalous statue of America's first president.

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

The largest cemetery for enslaved people in Loudoun County was almost lost to history, if not for the research of a minister.

A once celebrated industrial wonder now lurks in a quiet corner of Flathead Lake.

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

This twice-relocated "Usonian" home is among the smallest built by master architect Frank Lloyd Wright.

It should come as no surprise that the best view of the Hollywood sign is from Batman's lair.

The abandoned zoo enclosures offer a perfect place to experience the other side of the bars.

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 whole world in one water tank.

The remnants of a wooden-hulled fleet built and abandoned in WWI, now home to a thriving ecosystem.

This ruined quarry once produced the distinctive red sandstone used for construction projects in Washington, D.C.

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

A humble plaque marks the site where the country music legend was found dead in his Cadillac.

A favorite of Amelia Earhart, ranking among those rare bridges that can be crossed without changing sides of the river.

A circle of giant painted vases in the former pottery capital of the United States.

A tunnel with windows, so you don't miss out on the impressive views.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

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

This poor little statue is the most vandalized memorial in Washington.

The famous abolitionist’s preserved estate is one of Washington's finest monuments to its great Black citizens.