It is divided into seven rings or huge circles named from the seven planets, and the way from one to the other of these is by four streets and through four gates, that look towards the four points of the compass. Furthermore, it is so built that if the first circle were stormed, it would of necessity entail a double amount of energy to storm the second; still more to storm the third; and in each succeeding case the strength and energy would have to be doubled; so that he who wishes to capture that city must, as it were, storm it seven times. For my own part, however, I think that not even the first wall could be occupied, so thick are the earthworks and so well fortified is it with breastworks, towers, guns and ditches. When I had been taken through the northern gate (which is shut with an iron door so wrought that it can be raised and let down, and locked in easily and strongly, its projections running into the grooves of the thick posts by a marvellous device), I saw a level space seventy paces[1] wide between the first and second walls. From hence can be seen large palaces all joined to the wall of the second circuit, in such a manner as to appear all one palace. Arches run on a level with the middle height of the palaces, and are continued round the whole ring. There are galleries for promenading upon these arches, which are supported from beneath by thick and well-shaped columns, enclosing arcades like peristyles, or cloisters of an abbey. [Footnote 1: A pace was 1-9/25 yards, 1,000 paces making a mile.] But the palaces have no entrances from below, except on the inner or concave partition, from which one enters directly to the lower parts of the building. The higher parts, however, are reached by flights of marble steps, which lead to galleries for promenading on the inside similar to those on the outside. From these one enters the higher rooms, which are very beautiful, and have windows on the concave and convex partitions. These rooms are divided from one another by richly decorated walls. The convex or outer wall of the ring is about eight spans thick; the concave, three; the intermediate walls are one, or perhaps one and a half. Leaving this circle one gets to the second plain, which is nearly three paces narrower than the first. Then the first wall of the second ring is seen adorned above and below with similar galleries for walking, and there is on the inside of it another interior wall enclosing palaces. It has also similar peristyles supported by columns in the lower part, but above are excellent pictures, round the ways into the upper houses. And so on afterwards through similar spaces and double walls, enclosing palaces, and adorned with galleries for walking, extending along their outer side, and supported by columns, till the last circuit is reached, the way being still over a level plain.