Just beyond the western fringe of the Dunhuang oasis, not far from the river and the location of the "Western Thousand Buddha Caves" is a very impressive Han-era watch tower, which was part of the defenses leading out to the Yang Guan or Southern Gate. The tower overlooks (to the left in the photo) a replica of a portion of the Dunhuang walls and old city, built a decade or two back as a movie set. In the background are the impressive Mingsha sand dunes that lie between Dunhuang and the more distant snow-capped mountains.