Next to the Sitting Room is the Crimson Room or Old Study, where Paul I was in the habit of working. The room's architectural decor is restrained: a white moulded cornice in the classical style and a modest marble fireplace with an over-mantel mirror, also in the classical style. The walls of the Crimson Room are hung with large panels, the work of Semion Shchedrin, Professor of the Academy of Arts, one of Russia's pioneers in landscape painting. The panels were done in 1797-1800 on the order of Paul I, for the St Michael Castle; they picture some of the beautiful spots in the park at Gatchina.

The furniture is typical of the late eighteenth century: carved and gilded, upholstered with crimsoh silk. Special mention should be made of such interesting pieces of furniture as the bureau and the card-and checker-table by David Roentgen. The large long-case clock surmounted by a figure of Apollo holding a lyre is the work of David Roentgen, with movement by Peter Kinzing who also fitted it with a musical mechanism which plays a selection of pieces, in sounds resembling the flute and harpsichord.