This beautiful small marble mosque is situated at the north west corner of the Macchi Bhawan at the level of Diwan-i-Khas and Shahi Hammam overlooking the large court of the Diwan-i-Am. It was built by Emperor Shah Jahan in 1635-36 AD for the use of the nobles and officers who came to attend the Diwan-i-Khas functions. This rectangular maqsura or prayer chamber is two bay deep with three arched openings in the facade. The central arch is larger than the side ones. The chhajja, protecting the facade is curved in the middle above the central arch and parapet, indicating the Bangala influence in its construction. The structure is surmounted by three bulbous Mughal domes crowned by lotus-petals and kalash with metallic finials. The central dome is larger than the side ones. The central court has a small water tank with cascade for wazu. The prayer chamber is notable for the inlay in black marble the place of prayer (musalla) in the white marble flooring. There are ornamental marble railings in the court adjacent to the prayer hall. The mosque is elegant though very simple when compared with its successor Moti Masjid made of chaste marble in Red Fort Delhi, built by Aurangzeb in 1658-59.
The flooring of the prayer chamber is inlaid with prayer spaces (musallas) and at the further end is a small chamber overlooking the open area of the Diwan-i-Am. The local guides wrongly state that this mosque was built by Aurangzeb after the confinement of Shah Jahan. According to authentic contemporary histories Shah Jahan was never imprisoned but simply confined to certain parts of the palace, apparently in the Khas Mahal areas. The mosque was evidently built by Shah Jahan as is proved by the multifoiled cusped arches and elegant marble pillars of Shahjahani style. The mosque was used by Shah Jahani noblemen who came to attend the Darbar in the Diwan-i-Khas in the evenings.