What on Earth?

Satellite images capture evidence of an abandoned town hidden in the American wilderness, and as experts analyze this new evidence, they reveal what this strange place has to do with a top-secret military plan to battle an army of the undead.

Crop circles spotted on an island in the Mediterranean might not be from aliens, but from a threat closer to home: Nazis; new discoveries help experts uncover who made them and for what sinister purpose.

Satellite images capture a volcanic island that suddenly appears in the Pacific Ocean, and when NASA scientists arrive to investigate, they are baffled to find it’s home to a primordial slime and zombie creatures with origins in outer space.

Satellite images capture evidence of a mythical lost pyramid in China that's been hidden for centuries, and experts suspect it could be just one of many unknown structures used as a secret military base designed for subterranean nuclear warfare.

The remains of an abandoned settlement high in the mountains of Peru could be an ancient Roman village, leaving experts to speculate if the Romans visited the Americas centuries before Columbus; if so, it could point to long-lost gold.

Mysterious satellite images lead an archaeologist to investigate a cemetery on Devil's Island, the notorious penal colony in the tropics of South America; what he finds there reveals evidence of grisly executions that fueled a shark feeding frenzy.

Satellites capture a temple-like, Nazi structure hidden deep in the forests of Poland, leading an expert to investigate and uncover a tale of terrifying rituals, black magic and the rise of the most feared division of Hitler's war machine.

Satellites capture two strange patterns in the desert – and they are right next to Area 51; experts use cutting-edge science and new revelations from declassified documents to reveal what they are and what they mean.

When satellites spot a strange, 2,000-year-old structure in Wales, some suspect a secret connection to King Arthur; using modern-day technology and ancient texts, experts investigate new leads that could point to the mythical Round Table.