Mardin occupies a superb situation at the summit of one of the eminences which are ranged like a wall along the northern border of the Mesopotamian plain. All trace of an intervening plateau has here been completely eliminated; and from the foot of the declivity the ground stretches away to the southward in one illimitable level. The furthest identified landmark, a huge _tel_ rising conspicuously in the far distance, was pointed out to us as Tel Kokab nearly eighty miles away. These mountains are the Jebel Tur, the Mount Athos of the extreme east. They are a wild and barren district, containing very few villages, but thickly studded with ancient Christian monasteries; some of which date back to the seventh, eighth and ninth centuries, and most of which are still occupied by small companies of Syrian monks.[30] Mardin is situated at the western extremity of this region; and the northern and eastern boundaries are formed by a loop of the Tigris, which flows behind the upland from Diarbekr to Jezire ibn Omar and issues there on to Mosul plain. The hill on which the city stands is of a form which is not uncommon among the Kurdistan highlands, It rises from the plain in a single steep slope, unbroken almost from base to summit; but it culminates in a cresting of precipitous rock, so even and vertical that it looks like an artificial wall. Immediately behind the city this cresting forms an isolated knoll, cut off at the back and ends as abruptly as along the front, and thus forming an immense table with a perfectly level top. Many of the hills adjoining are of similar conformation; and another, almost a replica of it, may be seen in the mountains further eastward, forming the site of the town of Amadia. Amadia is built entirely on the level top, and the encircling line of precipice serves it instead of a rampart: but at Mardin the space on the summit is only sufficient for the citadel, and the town lies just at the foot of the precipice, sprawling down the southern slope of the hill. The houses look forth across the plain, each over the roof of its neighbour; and as even the lowest rank must be fully 1500 feet above plain level, they form a conspicuous assemblage visible for scores of miles away.