It might be called Britannia, but none of the arresting scenery is actually Albion.
Much of the drama was filmed in the Czech Republic and the most spectacular locations can be found in Wales. Here's where.
1. Rhossili Bay, Gower Peninsula
In the opening episode, Cait frolics on a golden beach with her spear. That gorgeous beach can be found on South Wales's justly famous Gower Peninsula – a haven of silken sand and dramatic limestone cliffs only a short drive from Swansea.
"Rhossili Bay has been voted one of the top 10 beaches in the world and the best beach in Europe," says location manager Gareth Skelding. "It’s a go-to location because it’s really spectacular and accessible for film crews. We were lucky because the weather was glorious."
2. Nash Point
It's little wonder Divis – the Druid outcast – looks so amazed. Nash Point is a headland west of Cardiff, near the village of Marcross, and it really is that spectacular, promises Skelding.
"The rock structure is almost like the Welsh version of Northern Ireland’s famous Giant’s Causeway."
Skelding's crew built a village on top of the cliffs. What you don't see in the drama is Nash Point's best known landmark: a 19th-century lighthouse.
He recommends climbing down to the beach for a walk, but treading carefully. "Wales has got the second highest tidal range in the world so anyone who does go there needs to be very careful because the tide can come in and catch you off guard very quickly. But it’s certainly worth the walk.
"And stay away from the rock edges. It looks amazing but it can be quite unstable – like a big game of Jenga!"
3. Henrhyd Falls
The crew's next stop was Henrhyd Fall, a waterfall at the foot of the Brecon Beacons.
"Henrhyd is the highest waterfall in South Wales and it’s one that you can actually walk behind. So you can walk right behind the water flow and look out down the valley, which is pretty cool. We had a few stunt guys on top and had one of them jump off which was quite a challenge!"
Henrhyd is managed by the National Trust, who have a car park nearby. After you've admired it, you can walk down the lovely Nant Llech Valley.
For more information on Henrhyd Falls and the Nant Llech walk, go to nationaltrust.org.uk/brecon-beacons/trails/henrhyd-falls-and-nant-llech-walk
4. Llyn Y Fan Fach
"Llyn Y Fan Fach is an amazing lake right at the top of the westerly tip of the Brecon Beacons.
"Accessing these beautiful places is always a challenge when you’ve got a film crew of a hundred people and horses. We had to install a bridge over a weak bridge, but it was worth the effort so we could get everything and everyone in that we needed to to make it look so fantastic."
A few years ago, the Lonely Planet named Llyn Y Fan Fach as one of the 1,000 must-see sights across the globe.
There's a folklore legend connected to it: the Lady of the Lake. The story goes that in the 13th century a local lad spotted the most beautiful woman he’d ever seen. She was a fairy maiden, who agreed to marry him on one proviso – he must not hit her more than twice. When he did, she disappeared back into the lake, taking her magic cattle with her.
Llyn Y Fan Fach is southeast of Llandovery. There’s a car park at the bottom and then it’s approximately a mile and half walk up the track to the lake.
5. Cwm Porth
Skelding's favourite location is also in the Brecon Beacons: Cwm Porth. Popular with potholers, it's where the River Mellte vanishes into a cave.
"You see it in the opening shots of one of the episodes. The water flows inside the cave and we were inside the cave looking out. "It’s fresh water straight off the mountains. I’m sure you could drink it.
"We flew a drone through the cave entrance and out onto the water face outside, so it was a spectacular shot and a technical achievement for the drone pilot. We did quite a few stunt sequences there, so we had rescue divers in the water and ambulances standing by."
The Four Falls Walk begins at Cwm Porth, and then meanders along a dried river bed and a woodland stream to Sgwd Clun-Gwyn – the "fall of the white meadow". It's actually two falls, which were also used as filming locations. The third waterfall is Sgwd y Pannwr, which used to be where locals washed wool, and the fourth is Sgwd yr Eira, the "waterfall of snow".
Britannia is on Thursdays on Sky Atlantic at 9pm