Bhismaknagar Fort is one of the oldest and most important archaeological sites in Arunachal Pradesh, known for its ancient history, stone architecture, and cultural significance. Located near Roing in the Lower Dibang Valley district, the fort dates back to around the 8th–12th century and is associated with the legendary King Bhishmak from local mythology. The structure is built with stone blocks and burnt bricks, featuring massive walls, gateways, living quarters, and remnants of ancient craftsmanship. The site reflects the historical connection between early tribal kingdoms and the spread of Assamese–Tibeto-Burman culture in the region. Surrounded by lush greenery and peaceful landscapes, Bhismaknagar Fort offers both historical insight and scenic beauty, making it a meaningful place for history lovers, researchers, and travellers interested in ancient heritage.