Jahaniyan Mosque is the latest of all the surviving monuments of the Sultanate period in gaur. It is also called 'Jan-Jan Miyan's Mosque' or Jhanjhania Mosque. From an inscription over its doorway it is known to have been built by Bibi Malti, probably a lady of the court, in 1535 AD, during the reign of Sultan ghiyasuddin mahmud shah, son of Alauddin husain shah. The nomenclature 'Jahaniyan Mosque' is rather obscure. It is believed that it might have been a corruption of a saint's name, Jahaniyan Jahangasht.
The building is situated a little to the south of the tomb of shaikh akhi sirajuddin usman to the northwest of the Sagar Dighi in the Indian part of Gaur-Lakhnauti. It is a brick building, the measurement being 17.5m × 12.8m externally and 12.20m × 8m internally. Inside, the mosque is divided into two aisles, each having three square bays surmounted by domes on stone pillars. The mosque has three entrances on its east side and octagonal towers at the corners with Mughal pinnacle turrets, an evidence of later Mughalisation. The moulded cornice at the top has a curvature representing the Bengali hut.
The wall faces of the building have been patterned with vertical offset and inset panels divided by horizontal string mouldings seen prominently first in the chika building and in the corner towers of the dakhil darwaza, and then fully developed in the kadam rasul. The building, together with the Kadam Rasul, forms a group easily distinguishable from other monuments of Gaur. [ABM Husain]