Perspective view of Sirenum Fossae in the Southern Highlands of Mars. The image shows the region centred at about 28°S / 185°E. It extends about 230 km by 127 km and covers 29 450 sq km, roughly the size of Belgium. The largest impact crater here is around 50 km in diameter, and indicates that this region is ancient because such large craters rarely form in more recent times.