The Blunt Force Gamer website has posted a video unpacking of the Citadel Realm of Battle gameboard.
From their announcement:
The Citadel Realm of Battle Gameboard is a first for Games Workshop. Composed of six 2?x2? modular tiles, the Gameboard can be built in a number of ways, broken down between games and kept safe and sound inside its own canvas storage bag. Here I open the bag for the first time and show everyone what the panels look like and the storage.