The Seven Wonders are the engineering marvels built by great minds of long-lost civilizations, but we're not sure if some even existed. New discoveries & cutting-edge archaeological methods might prove what they looked like and why they disappeared.

Seven wonders of ancient Egypt are home to mysteries still unsolved thousands of years after their construction, and today, investigators use cutting-edge tech and forensic analysis to reveal new secrets of these colossal engineering marvels.

America before Columbus was home to some of the greatest engineering marvels on the planet; special access to hi-tech archaeological digs reveals the secrets of ancient America's Seven Wonders as experts investigate their mysterious purposes.

Cutting-edge archaeological methods help experts unearth the dark secrets hidden at seven wonders of ancient Rome; what they find challenges everything we know about this once-mighty empire.

Experts explore Hadrian's Villa, the largest Roman palace ever constructed.

Egypt's ultimate secrets could be hidden underwater, and a cutting-edge archaeological investigation uses hi-tech methods to scan the ocean floor in search of sunken sphinxes, temples, and shipwrecks.

Seven American engineering marvels are among the modern wonders of United States, and now, investigators use hidden records to decode and reveal the mysteries behind these historic American icons.

Experts investigate myths of a secret portal to hell in Hierapolis.

Experts reveal the secrets of the Persian Empire's capital, Persepolis.

Nearly a decade after the ancient site of Nimrud was destroyed by terrorists, experts return to salvage the wreckage; archaeologists piece together the remaining ruins to reveal the origins and brutal decline of a lost empire.

The magnificent tomb of Alexander the Great mysteriously vanishes and becomes a legend; using CGI, investigators piece together the evidence to reveal where his tomb lies and what it might look like.

We reveal the centuries-old secrets and mysteries of one of the most remarkable examples of Victorian engineering. Follow the cutting-edge technology that built the Palace of Westminster, and find how it paved the way for the today's skyscrapers.

New discoveries might lead investigators to the legendary group of 300 Spartan warriors who died fighting off one million invading Persians, and using cutting-edge tech, experts reconstruct the battlefield to uncover the secrets of their last stand.

When Pompeii was destroyed by an apocalyptic volcano in 79 AD, another Roman town was destroyed, too; experts use cutting-edge tech to investigate the secrets of Vesuvius's second victim, which is one of the most perfectly preserved Roman towns on earth.

The Leaning Tower of Pisa is one of the world's most iconic buildings, and it's also the site of an 800-year-old mystery; using cutting-edge tech, experts investigate the archaeological evidence to reveal when it might finally fall over.

A strange site called Saqqara is home to Egypt's very first pyramid. Here, experts use cutting-edge tech to reveal why the ancient Egyptians started building pyramids and if the mummified animals found here are evidence of a bizarre religious cult.

The Dendera Temple is one of the best-preserved temples in all of Egypt; experts decipher its mystifying zodiac images and uncover the ceremonial events that took place at this sacred site, and stunning CGI rebuilds this grand complex in its prime.

The Roman Empire built Hadrian's Wall to guard its frontiers at the edge of the world; new discoveries reveal who the Romans were trying to keep out with this 72-mile-long megastructure and what it tells us about the ancient people of Iron Age Britain.

Pyramids in the deserts of Sudan are the ruins of a powerful lost civilization that rivaled the pharaohs of ancient Egypt. Using cutting-edge tech and archaeological methods, experts are revealing the secrets behind the mysterious Kingdom of Kush.

Experts travel inside ancient mounds to investigate the legend of Midas.

Experts investigate an ancient temple monument on an Egyptian island.

The coliseums of Rome were brutal theaters of spectacle and death that helped control the sprawling Roman empire; now, archaeologists uncover the engineering secrets behind these majestic structures to reveal the truth behind the ancient Roman world.

Palmyra: pearl of the Syrian desert; experts return to the site and use CGI reconstruction to reveal the secrets of Palmyra's ancient engineers.

The Great Wall of China is the biggest man-made structure on the planet -- and one of its biggest mysteries. Follow the scientific mission to reveal the ancient secrets of one of history's greatest empires.

The Tower of London is a centuries-old castle shrouded in a grisly past.