This harrowing climb along West Virginia's jagged spires is one of the only Via Ferrata on America's east coast.

Bubbling up from deep underground is the warm crystal clear water that fills the Warm Springs Pools, America's oldest spa.

This lookout tower built in the 1930s is now an in-demand cabin with what might be the best view of the Seneca State Forest.

The highest point in Maryland is only accessible by hiking through another state.

This beautiful stone arch bridge wasn't even expected to stand for one day, but people have been crossing it for centuries.

A remarkable time capsule of American manufacturing deep in Maryland coal country.

Maryland's first (and last standing) toll house on America's first federal road established the state as the "Gateway to the West."

This one-room cabin where the young colonel slept during the French and Indian War.

Despite violent work crews and massive delays this abandoned canal tunnel was built to last into the modern day.

Unannounced visitors are now welcome at the site of the largest Prohibition-era bootlegging operation in the region.

The smallest covered bridge in Maryland.

The longest-covered bridge in the state of Maryland.

The slate extracted from these Pennsylvania quarries was once hailed as the finest in the world.

Once the supplier for noteworthy projects like the National Cathedral, this old brickworks now lies abandoned.

A historic cemetery with unique artwork, a Civil War fort, and also happens to be the site of the Battle of Bladensburg.

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

An astounding collection of medical specimens, including bits of President Lincoln.

A lonely memorial to the Challenger Space Shuttle, honoring the astronauts who died in 1986.

The first dish to bounce radio signals off the Moon, it was the forerunner to the U.S. Space Program.

Using a massive antenna made up of five miles of wire, two scientists tuned into organic radio waves from the planet Jupiter.

This former asylum for Black Americans is haunted by its history of violence and racism.

The Virginia farm where John Wilkes Booth met his grisly end is now largely forgotten.

The rock on which Moll Dyer was found frozen to death is said to still bear her handprint.

The Forest Service's surprisingly sophisticated collection of wildfire prevention art features America's most beloved bear.