Constructed in 1676, this stone memorial is believed to be the oldest veteran's memorial in the United States.

An abandoned stretch of highway, deteriorating next to the operational one.

Once damaged by Hurricane Agnes, this bridge is now on the National Register of Historic Places.

Berkeley Hot Springs presents to you "the only outdoor monument to presidential bathing."

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.

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

The ruins of an abandoned 18th-century town that is slowly being reclaimed by the forest.

Mysterious stone tower featured in many alternative histories of the New World.

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

A small brick parlor house and artist's studio located in the wilderness is surrounded by imposing suburban palaces.

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

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

This suburban house is made of dirt, and almost sparked a revolution in home construction.

This massive swimming pool is the high tech home to the human-powered submarine races.

This sprawling farm was once a Cold War-era hideaway for the nation's top diplomats.

A former special storage facility for documents during the Cold War.

Three abandoned missile silos are hiding in plain sight behind a suburban development in Maryland.

Proto-CIA agents trained with grenades in the sand traps and fired machine guns from the fairways.

Was there a small "backpack nuke" hidden in the attic? JFK apparently thought so.

A cenote sitting in the middle of a parking lot shows the Yucatán Peninsula at its most urbanized.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

Abandoned Coast Artillery fort now serves as a graffiti canvas and sightseeing vantage point.

A hacienda that features all things uniquely Yucatán.