Perched on a spur above the confluence of the Drangme Chhu and Gamri Chhu, Trashigang Dzong is one of the largest fortress-monasteries in Bhutan. The whitewashed walls rise sheer from the rock, capped with the deep red and gold roofs that mark every dzong. From the courtyard you look straight down into the gorge, which is the point — the founders chose a site that didn't need outer walls because the geography was a wall already.
Inside, the dzong houses both the district administration and a working monastic body, with about 200 monks in residence. The main lhakhang holds large images of Buddha and the founder Zhabdrung Ngawang Namgyal, and the wall paintings are typical Drukpa Kagyu style — the protectors of the four directions, the wheel of life, the lineage masters. The Tshechu festival in November or December fills the courtyard with masked dancers, and is the best time to visit if you can match the dates.
Access is by a short steep walk up from the road. Photography inside the temples is not permitted; the courtyard and exterior are fine.