Bhismaknagar is the oldest ancient archeological and heritage site near Roing in Lower Dibang Valley District in the northeastern state of Arunachal Pradesh in India. The place is almost 30 kilometers away from Roing town. The place has its link with the great Indian mythology ‘The Mahabharata’ and it is also a symbol of the past glory of 12th century AD which indicates the high standard of civilization that once prevailed in the Chutiya Kingdom. The excavation project for this site was started in 1969 and was completed around 1973. The ancient archeological site was built during 8th century by a Chutiya kingdom and it was again rebuilt by another Chutiya King Gaurinarayan. From 12 to 16th centuries Bhismaknagar must have been a stronghold of Chutiya Kingdom. A site is an important place of heritage for the Chutiya Kingdom. Bhismaknagar is surrounded by a wall of 4.5 meters high and 6 meters wide made of granite stones.

The area of Bhismaknagar is extended over 1860 square meters which displays three halls, six ingresses, and two extension rooms. Inside the complex there is also a 2 meters high stone wall and each and every architecture of the fort displays the medieval culture. There are many works of art like potteries, terracotta figurines, terracotta plaques, and decorative tiles in the fort and are well preserved. Fabricated from the burnt bricks gave this fort an impressive and remarkable top view and thus explores the dexterity of people of the ancient era. This fort can still be signified as an astonishing work of art. The Idu Mishmis tribal communities of Arunachal Pradesh believe this Bhismaknagar ancient archeological site as a holy heritage site.