The contents of this safe survived a 37-kiloton nuclear bomb.

The only nuclear weapon assembly and disassembly plant in the U.S.

Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.

An abandoned underground bunker not far from downtown New Orleans.

Built in just a little over a week this preserved bunker was created to protect our most attractive POTUS while he was on vacation.

America's post-nuclear-attack chambers of Congress.

A lone historical marker off the highway and scattered debris are all that remain of this Cold War-era missile site.

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.

This icon of the Atomic Age now lays dormant.

A hyper-luxurious, 12,000- square foot home might be buried beneath Queens, still waiting to protect you from nuclear missiles.

This was one of the first (and last) university-built and operated nuclear reactors.

World's first "penitentiary," meant to be humane, drove men insane.

America's greatest forgotten garden and the former stomping grounds of Son of Sam.

Along the Palisades skyline are the ruins of a large mansion built in 1911 and demolished in the 1930s.

Decades after testing the polio vaccine on unwitting patients, this historic mental hospital sits in ruin.

A modern ghost town whose inhabitants were driven away by the growth of nuclear power.

A ruined mansion hidden in the woods of the Hudson Valley, home of a tragically doomed romance.

Once in a state of dilapidation, this candy-inspired fortress is now being revived.

These beautiful ruins deep in the Pennsylvania woods are thought to have been a ski lodge or a speakeasy, but no one really knows.

Buildings that dynamite couldn't bring down were abandoned because of bathroom issues.

A marine aquarium with an astounding variety of fish hides in the basement beneath the famous Palm House.

Hidden in a grotto 26 feet below Nottingham's oldest hotel, this stylish subterranean drinking den is notoriously hard to find.

A labyrinthine underworld of tunnels and caverns hides beneath the city.