This is the largest room in the castle, where the Fosdinovese people witnessed the public birth of the heir of the Marquise Maria Cristina Pallavicini, Carlo Agostino.
The name derives from the particular shape of the windows called, in fact, the Mullioned windows, typical ornament of the nineteenth-century neoclassical taste.
In the bathroom a Carrara marble bathtub, a single block sculpted on site.