Khaniyadighi Mosque (Bengali: খানিয়া দীঘি মসজিদ), also known as ‘Rajbibi Masjid’, is a historical architecture of Bangladesh located near the small Sona Mosque in Chapainawabganj district, Rajshahi. The building is now in a good state after thorough repairs undertaken by the Directorate of Archaeology, Bangladesh. The mosque is situated on the bank of Khania Dighi, about a quarter of a mile from the high mud wall of the ancient city of Gaur on the north and the Balia Dighi on the west in the district of Nawabganj. Constructed around the 15th century, it is considered one of Gaur’s oldest plays. It is believed that the mosque was built by a Rajbibi in 1460 AD. The mosque looks more like the mosque of Maldar Chamkati. The mosque is constructed mainly of bricks and consists of a square prayer room, 9m aside, and a 9m’ 3m verandah in the east. The prayer chamber is roofed over by an enormous hemispherical vault, while the verandah is secured by three little arches. The huge vault of the petition chamber is continued half-domed squinches on the corners and blocked curves on the four cardinal sides and the pendentives in the middle of the curves. The verandah’s three small domes are built on pendentives. Three verandah arches that correspond in height and width to the three archways on the eastern façade and a single archway on the north and south sides join the prayer hall. The four outside edges of the structure are set apart by octagonal pinnacles rising up to the rooftop level. Two different pinnacles recognize the focuses where the verandah joins the petition chamber. All the pinnacles are separated into areas by raised groups. The cornice of the structure is marginally bended.
The area of this mosque is 72 × 42 feet. It’s a 14th-century mosque, a valuable archeological heritage of Bangladesh. The qibla wall, recessed with three semi-circular mihrab niches corresponding to three eastern archways, is fully veneered with granite stone blocks within. Stone blocks were also mounted on three other walls within the prayer hall, in the shape of a lintel at the springing point of the arches. Similar kind of stone squares framing the lintel has been stretched out to the verandah dividers. The blocked-curves and squinches which uphold the vault above are raised over stone sections installed into the dividers. The two east-west curves which have partitioned the inside of the verandah into three sections are likewise continued connected with stone segments. Of the three mihrabs, the central one is larger than the side ones and shows outward rectangular projection along with the wall height. Both of these mihrab niches, enclosed within a rectangular framework, are arched in the face with cusping. The structure underneath the principle vault is square fit as a fiddle, with each arm estimating 26 feet long. The entire structure was once decorated with earthenware ornamentation, hints of which get by to a great extent both inside and outside the structure. It is important to note that the mosque, consisting of a single-dome prayer hall and an east-facing three-dome verandah, marks an improvement over the simple single-dome square style that was so common in Bengal. Today, only a single dome and a portion of the mosque’s walls remain. But they are still in a very dilapidated state.