Bara Jamalpur Mosque is located at the village Bara (bada) Jamalpur under Sadullapur Thana of Gaibandha district, about 12 kilometres east of Pirganj Thana headquarter, and 6 kms due west of Sadullapur Thana headquarter.
This rectangular three-domed mosque is raised on a low plinth and measures internally 11.40 meters from north to south and 3 meters from east to west. Externally, it measures 13.90 meters by 5.50 meters. There are three arched entrances in the fašade wall, of which the central one is slightly larger than the flanking ones. There is an arched window filled with brick grills in the north and south walls. The qibla wall of the mosque is provided with a single mihrab on the axis of the central entrance. The mosque does not have any corner tower. On the parapet wall there are eight minars - four on the fašade wall and the rest on the back wall. Cupolas with kalasa and lotus-bud finials cap these minars.
Two lateral arches divide the interior of the mosque into three bays, each covered with a dome with an octagonal drum. The central bay is slightly larger than the side ones. The thrusts of the drums are directly carried on the lateral arches. The corners are filled with beautiful Bengali pendentives. The central dome is larger than the flanking side ones. The domes are crowned with full-blown lotus flower designs and finials of kalasa and lotus bud. Once the mosque compound was enclosed by a wall, but at present this has fallen down and can be traced only in a few places. Recently, a box type veranda has been added in front of the mosque.
There is no epigraphic evidence of its date. But local tradition relates that Haji Jamaluddin, who lies buried on the northern side of the mosque compound, built it. It is said that he was a revenue officer of the local Mughal administration. There may be some truth in the tradition because the village in which the mosque is situated is named after him. On the ground of its stylistic similarity with the dariyapur mosque, which is about 20 kilometers away, an early 18th century date may be suggested for the mosque.