From a revolutionary war era ship hiding under the streets of Manhattan, to a sprawling Roman villa unearthed in the backyard of an English home, or even an ancient Grecian maze long thought to be a myth--the strange structures uncovered in this episode sometimes lead to more questions than answers.

We explore some of the most valuable treasures found in the most unlikely of ways. Like a priceless Ancient Roman mosaic hiding in a New York city apartment, or the most valuable piece of Americana tucked away in a $4 flea market find. You never know where the next million-dollar discovery could be uncovered.

From priceless treasure found inside a lost city, to an ancient manuscript hidden behind a wall, explore mysterious secrets lost deep inside various unseen chambers, like tunnels, caves, or even burial sites.

From clandestine nuclear weapons programs to a secret Cold War bunker hidden in the mountains, or even World War 2 technology at the bottom of the sea, we explore the unlikely people, and surprising places behind the discoveries of the most top-secret information.

From ancient religious texts buried in Egypt to cultural relics found at sea, or even a tower of skulls hiding under the earth, these lost artifacts change what is known about certain sacred beliefs.

From a deadly discovery hiding under one of America's most loved national parks, to a Nazi era weapon sunk off the coast of New Jersey, or even a blood thirsty predator found in Canada--you never know where a killer find is hiding or who may stumble upon it.

From a mythical monster that turns out to be real, to a deadly prehistoric animal, and a frozen tundra hiding a pandora's box full of lethal pathogens, these startling discoveries shock and terrify the world.

From a Chinese curse that turns out to be real, to human remains in a Founding Father's basement, or even a mysterious island in Central Asia with enough pathogens to kill the entire global population several times over.

From a bat swung by one of baseball's boldest pioneers, to an iconic painting hidden behind a false wall, these astonishing finds prove that America's greatest treasures can turn up in the most unlikely places.

From WWII bombs pulled from the sea and Nazi bunkers buried in sand, to chemical weapons hidden beneath Washington, D.C., these explosive discoveries prove that history's blasts from the past can still shake our world today.

Some secrets refuse to stay buried. Whether it's illicit cargo in a frozen lake, a stolen masterpiece worth millions, or a brothel hidden in the shadow of the Capitol—the truth always resurfaces.

From a legendary city swallowed by the jungle, to an underground metropolis stretching 18 levels deep, and even a forgotten pyramid from a lost civilization, sometimes the biggest mysteries on Earth are closer than we think.

A forgotten manuscript in a dusty trunk. A priceless painting discovered in plain sight. A royal tomb hidden for millennia beneath the sands. These famous finds prove history's greatest treasures often resurface when least expected.

Forget the monsters under your bed. The real ones, from dinosaurs to mythic beasts, are out there just waiting to be unearthed.

Secrets of popes, rewritten laws, and cities lost to the waves — these divine discoveries shake our beliefs and uncover mysteries of truly epic proportions.

From a long-lost keepsake tied to the world's most famous astronaut, to a giant flying reptile that once ruled the skies, and even a previously unknown planet orbiting two suns…some extraordinary discoveries remind us to keep looking up.

The world's greatest fortunes often surface in the most unlikely places. From a Fabergé egg found at a humble flea market, to rare baseball cards hidden inside an old piano.

Beneath the earth, frozen in the tundra, and hidden in the depths of the sea, lie some of the deadliest discoveries of all time.