Watched hit Netflix show Ancient Apocalypse yet? Spread across eight episodes, controversial journalist Graham Hancock visits an array of ancient sites, and attempts to prove an outlandish theory – that an advanced Ice Age civilisation once roamed the Earth, spreading ancient wisdom to hunter-gatherers, before being wiped out in a great flood. Hancock suggests the sites featured in the show are far older than they appear and contain allusions to this advanced people, but most archaeologists are highly critical of his views, dismissing them as unfounded conspiracy theories. That's not to say the sites aren't genuinely mysterious – these are the real-life secrets hidden in the series' sites...