Restored by the army in the late 1990s, this tiny white cube of a temple is said to date back to the time of the 'Great Translator' Ringchen Zangpo (10th to 11th century). It sits on a steep, rocky crag whose higher slopes are dotted with the crumbling ruins of an ancient fortress. Inside, you'll need a torch to pick out the dark, intricate Alchi-era murals.
The site is around 1.8km up the eastern side of the vallley road from Phyang Gompa. Call the key-holder, carpenter Tsering Norboo, beforehand or it will be locked (his house is almost directly below the temple).
To reach the fortress (40 minutes) and its fine views follow the red Xs up a shoulder of ridge. Eventually you loop around the base of the upper castle clockwise to find a way up that's a bit of a scramble but doesn't require any real climbing.