Under a playground is a little-known sealed train tunnel that likely contains the bodies of workers trapped by cave-ins.

This pun was simply waiting to come to life, and one defense contractor made it so.

An overgrown garden stands as a grim marker of an unrealized dream.

This maze-like slot canyon is a unique gem within an already fascinating geological area.

Hidden for 165 years inside a building designed by Thomas Jefferson are the remains of what may be America's first educational chemistry lab.

An eight-sided home built during a brief octagon craze in the 1850s.

Hop on the train and tour an elaborate miniature town made completely of junk (including the train).

A double agent hid information for the Soviet Union beneath this bridge for more than 20 years.

A convincing little bit of ancient Egypt smack dab in Richmond, Virginia.

The Virginia home of one of the signers of the Declaration of Independence is being preserved with a unique glass facade.

Portland had a unique approach to Cold War-era protections.

The Cold War-era "underground Pentagon" is a sprawling subterranean hideaway for the Defense Department.

Herbert Hoover's "Brown House" rural presidential retreat was a PR disaster amid the start of the Great Depression.

Conveniently located within binocular range of a nuclear bunker, the "summer camp" area was a painfully obvious spy house.

This extensive nuclear fallout shelter built from 42 school buses could house 500 people in its tunnels.

America's only nuclear missile silo open to the public.

An overgrown collection of miniature buildings still stand as evidence of one couple's obsession with The King.

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

This war hero's old shop remembers the fine line between medicine and quackery during the Revolutionary War.

One street divides a single town that stands in two U.S. states.

One of the last active volcanoes on the Eastern seaboard.

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

A quintet of history museums make this Virginia graveyard as much a resting place for funereal history as it is for people.

This grave marks the passing of a historic Jane Doe whose identity remains a mystery to this day.