Dechen Phodrang, the "Palace of Great Bliss," stands on a hilltop spur overlooking north-central Thimphu. Although the origins of the monument date to as early as the 12th century, it was frequently reconstructed over the years to accommodate various functions.
Gyelwa Lhanangpa (1164-1224), the founder of the Lhapa Kagyupa school, is thought to have established the Dongon Dzong, an early fortress, at the site of today's Dechen Phodrang. According to Gersdorff and Pommeret, the Lhapa school instituted a joint religious and political rule, called the chosi, though it lasted only briefly. The early dzongs of the era—which were far simpler affairs than the "new model" dzongs introduced by the Zhabdrung Rinpoche in the 17th century—likely played a supporting role in this consolidation of authority.
The fortress seems to have remained in Lhapa hands until the early 17th century when the armies of the Zhabdrung Rinpoche assimilated the dzong and its environs into his nascent state. According to Phuntsho, he renamed the fort Trashichodzong and used it as a summer capital. The government and monastic body then rotated bi-annually between Thimphu in summer and Punakha in winter.
Somewhat confusingly, Trashichodzong is also the name of the sprawling capital complex located 1,250 meters to the south along the left bank of the Wang Chu river. The identical names are a consequence of the later history of Dechen Phodrang from the 18th century onward. In 1772, the original dzong at today's Dechen Phodrang was destroyed by fire. The sole surviving structure of note was the Zhabdrung's residence, which was renamed Dechen Phodrang. The monastic residence and government functions that had formerly existed at Trashichodzong were shifted to the new site to the south, which assumed the old name. Briefly, the 16th Druk Desi, Sonam Lhundub (known as Zhidar), attempted to name the site after himself, dubbing it Sonamchodzong. However, upon his death in 1773, the old name Trashichodzong was revived.
Since 1969 (or 1971), Dechen Phodrang has been used as a monastic school, called a lobra, that provides education for several hundred novice monks. The various dormitories of Dechen Phodrang are arranged in an arc following the ridgeline south of the main sanctuary.