HBO's Game of Thrones prequel series has started filming. 1 / 7
The show will take place thousands of years before Game of Thrones... 2 / 7
And explore the true origin of the White Walkers, among other things. 3 / 7
Naomi Watts is starring as "a charismatic socialite hiding a dark secret". 4 / 7
Production is now underway in Northern Island, where much of Game of Thrones was filmed. 5 / 7
The prequel may premiere in the same spring slot as Game of Thrones and Westworld. 6 / 7
If so, it probably won't arrive until early 2021, rather than next year. 7 / 7