The Simtokha Dzhong is a small Dzhong located approximately 5 kilometers south of Thimphu. The Dzhong is officially called the sangakZabhonPhodrang which roughly translates to the Palace of the Profound Meaning of Secret Mantras. The Simthoka Dzhong is said the be the first fortress to have been built by the legendary ShabdrungNgawangNamgyal in Bhutan. The fortress was constructed in the year 1629. Some suggest the Dzhong is the oldest surviving complete Dzhong in Bhutan. The Dzhong is currently home to the Institue for Languages and Cultural Studies which is attended by monks and common people alike. The site of the Dzhong is said to have been built over a site where a demon had disappeared in to the rocks nearby. The site of the Dzhong is located very strategically at a point from where the Dzhong can protect the Thimphu Valley and also protects the valley that leads to the Dochu La pass and onwards to eastern Bhutan.
The Dzhong was attacked during its construction by the Tibetans and a group of Bhutanese Lamas who opposed to the Shabdrung. Even though the initial attack failed the Dzhong was subsequently conquered in 1630. After a few failed attepmpts the Shabdrung regained control over the Dzhong when the Dzhongs main building caught fire and its roof collapsed on its occupiers killing them all. The Dhzong underwent many expansions and restorations ever since.