Dzong is the largest dzong fortress in Bhutan
, located in Trongsa (formerly Tongsa) in Trongsa district, in the centre of the country. Built on a spur overlooking the gorge of the Mangde River, a temple was first established at the location in 1543 by the Drukpa lama, Ngagi Wangchuk son of Ngawang Chhojey. In 1647, his great-grandson Shabdrung Ngawang Namgyal (Shabdrung or Zhabdrung being his title), constructed the first dzong to replace it, called Chökhor Rabtentse Dzong with a shorter version of Choetse Dzong. It was enlarged several times during the 18th century; the Chenrezig Lhakang was built in 1715 and a whole complex, including the Maitreya (Jampa) temple, was added in 1771. The dzong has since been repaired on several occasions; it was damaged during the 1897 Assam earthquake and underwent extensive renovation in 1927 and 1999.
Trongsa Dzong, the largest dzong at a striking location, is an important administrative building, providing the headquarters of the government of Trongsa District. Trongsa provides a strategic central location to control Bhutan and for centuries it was the seat of the Wangchuck dynasty of penlops (governors) who effectively ruled over much of eastern and central Bhutan, and from 1907 have been Kings of Bhutan. It is also a major monastic complex, with around 200 monks. During the summer months, the monastic community often relocates to Kurje Monastery in the Bumthang
valley. It contains a notable printing house, responsible for the printing of many religious texts in Bhutan.).
The Dzong and the small town surrounding it are situated on a spur, a wild rocky area, above the ravines of the Mangde Chuu valley with the scenic backdrop of the Black Mountains on its southwest. The Dzong is located above the fast flowing Mandge Chu in a unique setting that has been described as "the most spectacularly sited dzong in Bhutan with a sheer drop to the south that often disappears into cloud and mist".
A five day festival known as the Trongsa tsechu is held in the northern courtyard of the temple during December or January. Every monastery in Bhutan observes this festival, which celebrates the arrival of Guru Rimpoche to Bhutan in the 8th century, a mark of triumph of Buddhism over evil. It is held in spring and autumn seasons according to the Bhutanese calendar and masked dances are a popular feature along with the exposition of a very large thanka (religious painting) on cloth of Guru Rimpoche and other figures called the thongdrel. A fire blessing in the form of people running though "an archway of blazing straw" is also witnessed.