Tajpur Fort locally known as Killa Tajpur, is situated some six miles northeast of bokainagar fort. According to local traditions, the fort was built by Majlish Khan Humayun, a general of Sultan Saifuddin Firuz Shah II (1488-1490), during his campaign against kamarupa. During the heydays of the bara-bhuiyans towards the end of the 16th century, the fort was under the command of Nasir Khan and Daria Khan, allies of Osman Khan. In 1611, Nasir Khan and Daria Khan surrendered to the Mughals. After occupying the fort for a brief period, Osman Khan too fled and the fort fell to the Mughals. Thereafter, the fort served as the seat of local administration under the Mughals.

No structural remains of the fort exist today and the entire site has been turned into rice fields. However, a portion of the wall can still be seen standing in the site, along with innumerable brickbats and potsherds. A brick structure of the fort was accidentally exposed when the southeastern corner of its rampart was washed away by a branch of the Brahmaputra. The exposed structure is 4.57m high, 9.14m at the base and gradually tapers at the top. [Shahnaj Husne Jahan]