The building of the sanatorium is part of a former hospital complex. During WWI many injured soldiers stayed there, including Adolf Hitler.
Filmed at the Castle Hohenzollern in Hechingen, Germany.
The building of the sanatorium is originally located in Beelitz-Heilstätten, an old tuberculosis clinic. The building itself and the area around it have been completely renovated after being a ruin for decades. 750 windows (1,000 sq m of glass), 350 doors, 1,200 sq m of walls and many other things had to be replaced or repaired to restore the original look of the building.
For filming, Castle Hohenzollern was completely closed to the public from July 13 to July 24, 2015.
Although the story takes place in Switzerland, the film was shot in Germany.