A worker in the Great Hall of the Royal Palace in Vizima in The Witcher 3 Wild Hunt

Workers as seen in the Great Hall of the Royal Palace in Vizima in The Witcher 3: Wild Hunt.

These are Nordling peasants who got "volunteered" to "help" the Nilfgaardian Empire with the renovation of the conquered castle.

On orders of Emperor Emhyr, the workers follow instructions from the Royal Architect for renovation of the structure to match Nilfgaard interior design rather than Northern Kingdom design.