Located in the private area of the Red Fort Palace Complex between the Khas Mahal and the Imperial Baths, the Diwan-i Khas was the Mughal emperors' private audience hall. In some early accounts, the Diwan-i Khas was called the Ghasl Khana, or the washing room. This term may have arisen from the location of the hall close to the baths.
The Diwan-i Khas consists of an inner hall enveloped by a gallery. 21.03 meters wide and 27.4 meters deep, the spaces of the pavilion are defined solely by archways; its flat roof is carried on cusped arches falling on rectangular and square piers. The dados of the piers are ornamented with pietra dura, while the tops of the piers and the arches are decorated with paint and gold. The original ceiling was of silver, inlaid with gold.
Sources:
Mukherji, Anisha Shekhar. 2003. The red fort of Shahjahanabad. Delhi ; Oxford: Oxford University Press, 143-144.
Tillotson, G.H.R. 1990. Mughal India. San Francisco: Chronicle Books, 62-64
Williams, John A. and Caroline. 1980. Architecture of Muslim India. Set 8, Shahjahan (1627-1658): The Imperial Citadels. Santa Barbara, California, Visual Education Inc.