Grad Daga, Military fortress in Dagana District, Bhutan.

Grad Daga sits on a ridge overlooking the valley below, displaying traditional Bhutanese construction with detailed woodcarvings and hand-painted designs adorning its walls and roof elements. The structure houses monastic quarters, religious shrines, and administrative spaces arranged around interior courtyards in the typical dzong layout.

Daga Dzong was begun in 1649 on the orders of Zhabdrung Ngawang Namgyel, who sent Druk Namgyel to subdue the area and defend it against incursions from the southern states, present-day Assam and West Bengal. Local people helped with the construction, which was completed in 1651 and named Daga Trashiyangtse Dzong. An earthquake destroyed the whole dzong in 1897, after which it was rebuilt from the foundations and its temples and relics restored.

The name Daga comes from Darkala, the province's guardian deity, and Darkanang, "Realm of White Prayer Flags", given by the master Dudjom Jigdrol Yeshey Dorji. Zhabdrung Ngawang Namgyel named the completed dzong Daga Trashiyangtse Dzong and installed the first Daga Penlop. Eight shrines inside hold Jowo Shakyamuni surrounded by sixteen arhats, and the district monastic body still resides here.

The location sits high on a ridge and involves climbing to reach, so sturdy footwear is important for the walk up. As an active monastery undergoing restoration work, some areas may not always be open to visitors, so checking access conditions beforehand is wise.

The monastery holds an ancient buffalo horn dating to the early 1500s that measures over 4 feet (1.2 m) in length, serving as an important religious artifact. This object reveals how such fortresses often housed sacred items alongside their military functions.