At Göbekli Tepe, the oldest known megalith in the world, Graham questions if simple hunter-gatherers alone could have built such an advanced structure.
Graham visits ancient mounds in North America and wonders if they contain astronomical significance — or even warnings of an apocalyptic climate event.
In the ancient geological sites of North America, Graham envisions an apocalyptic event that may have changed the Earth — and its inhabitants — forever.
From ancient footprints to mysterious earthworks, Graham continues his journey into the past alongside experts and curious minds, including Keanu Reeves.
Although thousands of miles apart, Graham considers the possible link between the shamanistic use of ayahuasca in the Amazon and tobacco in New Mexico.
