Researchers believe extraterrestrial beings took part in building the great pyramids. See more in this clip from Nostradamus Effect. #NostradamusEffect Subscribe for more from Nostradamus Effect and other great The HISTORY Channel shows: http://histv.co/SubscribeHistoryYT Watch more ...

Researchers believe that many of the deadliest diseases come from outer space. See more in this clip from Mega Disasters. #MegaDisasters Subscribe for more from Mega Disasters and other great The HISTORY Channel shows: http://histv.co/SubscribeHistoryYT Check out exclusive The HISTORY ...

The threat of a possible alien invasion grows, in this clip from Season 1, "Doomsday: 10 Ways the World Will End." #CountdowntoArmageddon Subscribe for more HISTORY: http://histv.co/SubscribeHistoryYT Check out exclusive HISTORY content: History Newsletter - https://histv.co/newsletter ...