The situation of Mycenæ is beautifully described by Homer,[105] "In the depth of the horse-feeding Argos," because it lies in the north corner of the plain of Argos, in a recess between the two majestic peaks of Mount Eubœa, whence it commanded the upper part of the great plain and the important narrow pass, by which the roads lead to Phlius, Cleonæ, and Corinth. The Acropolis occupied a strong rocky height, which projects from the foot of the mountain behind it in the form of an irregular triangle sloping to the west.[106] This cliff overhangs a deep gorge, which protects the whole south flank of the citadel. Through the abyss below winds the bed of a torrent usually almost dry, because it has no other water than that of the copious fountain Perseia, which is about half a mile to the north-east of the fortress. This gorge extends first from east to west, and afterwards in a south-westerly direction. The cliff also falls off precipitously on the north side into a glen, which stretches in a straight line from east to west. Between these two gorges extended the lower city. The cliff of the citadel is also more or less steep on the east and west side, where it forms six natural or artificial terraces. [Illustration: No. 17. Walls of the First Period.] The Acropolis is surrounded by Cyclopean walls, from 13 to 35 feet high, and on an average 16 feet thick. Their entire circuit still exists, but they have evidently been much higher. They are of beautiful hard breccia, with which the neighbouring mountains abound. They follow the sinuosities of the rock, and show three different kinds of architecture. By far the greater portion of them is built exactly like the walls of Tiryns, although not so massively; and as this kind of architecture is generally thought to be the most ancient, I have marked it on the adjoining cut (No. 17) with the words, "Walls of the first period." A large piece of the western wall I have marked on the accompanying cut (No. 18) as "Walls of the second period," because it consists of polygons, fitted together with great art, so that, in spite of the infinite variety of the joints, they formed as it were one solidly united and neat wall, as if of rock; and this sort of building, which can be seen in so many places in Greece and Southern Italy, is universally acknowledged to be generally of a later period than the former. I have marked here (No. 19) as "Walls of the third period" those walls to the right and left of the great gate, which consist of almost quadrangular blocks arranged in horizontal layers; but their joints are not always vertical and they present lines more or less oblique. [Illustration: No. 18. Walls of the Second Period.] [Illustration: No. 19. Walls of the Third Period.] [Sidenote: THREE KINDS OF PRIMITIVE WALLS.]