If there was really a northern as well as a southern Ecbatana, and if the account of Herodotus, which cannot possibly apply to the southern capital, may be regarded as truly describing the great city of the north, we may with much probability fix the site of the northern town at the modern Takht-i-Suleiman, in the upper valley of the Saruk, a tributary of the Jaghetu. [PLATE I., Fig. 3.] Here alone in northern Media are there important ruins occupying such a position as that which Herodotus describes. Near the head of a valley in which runs the main branch of the Saruk, at the edge of the hills which skirt it to the north, there stands a conical mound projecting into the vale and rising above its surface to the height of 150 feet. The geological formation of the mound is curious in the extreme. It seems to owe its origin entirely to a small lake, the waters of which are so strongly impregnated with calcareous matter that wherever they overflow they rapidly form a deposit which is as hard and firm as natural rock. If the lake was originally on a level with the valley, it would soon have formed incrustations round its edge, which every casual or permanent overflow would have tended to raise; and thus, in the course of ages, the entire hill may have been formed by a mere accumulation of petrefactions. The formation would progress more or less rapidly according to the tendency of the lake to overflow its bounds; which tendency must have been strong until the water reached its present natural level--the level, probably, of some other sheet of water in the hills, with which it is connected by an underground siphon. The lake, which is of an irregular shape, is about 300 paces in circumference. Its water, notwithstanding the quantity of mineral matter held in solution, is exquisitely clear, and not unpleasing to the taste. Formerly it was believed by the natives to be unfathomable; but experiments made in 1837 showed the depth to be no more than 156 feet. The ruins which at present occupy this remarkable site consist of a strong wall, guarded by numerous bastions and pierced by four gateways, which runs round the brow of the hill in a slightly irregular ellipse, of some interesting remains of buildings within this walled space, and of a few insignificant traces of inferior edifices on the slope between the plain and the summit. As it is not thought that any of these remains are of a date anterior to the Sassanian kingdom, no description will be given of them here. We are only concerned with the Median city, and that has entirely disappeared. Of the seven walls, one alone is to be traced; and even here the Median structure has perished, and been replaced by masonry of a far later age. Excavations may hereafter bring, to light some remnants of the original town, but at present research has done no more than recover for us a forgotten site.