(_a_) Passages were evidently constructed as part of the plan of the fortifications, but in some instances only as means of communication between certain buildings within the fortified area and for securing privacy. In the one class of passage buttresses and traverses are repeated with a marvellous redundancy; in the other class of passage not a single buttress or traverse is to be found. (_b_) In passages leading from main ruins to exterior buildings the walls of the passage nearer the main ruins are better built, and the steps and floors are better constructed in the portions nearer the main ruins than are those of the more distant portions of the passage. So imperceptibly do the better-built portions merge into the less superior class of wall that it is extremely difficult to ascertain the exact point where the change in the quality of the construction takes place, though the difference in the class of building at one end of the passage and that of the other is most obvious. But though this difference in the construction of the passage walls is so apparent, there is no suggestion that portions were of a later period, for they are built upon one plan, have one line of direction, serve as a complete communication with one obvious and particular point, and one length of the passage without the other would be purposeless, so far as the intention of the builders may be gathered. With regard to the passages ascending the Acropolis Hill, the completeness of the plan of these passages is best seen from the summit of the hill or from the summit of Makuma Kopje on the opposite side of the valley, from which heights respectively a complete view of those passages in their entire length is to be obtained. (_c_) Excepting some of the passages in the Elliptical Temple and a few others on the Acropolis, all the passages at Zimbabwe are exceedingly narrow and tortuous, many being only shoulder wide, while, owing to their winding lengths, it is not possible to see many feet on ahead. Such of these passages as have their floors below the levels of adjoining enclosures have in many places their side walls bulged by the weight of earth and débris behind into the passage-ways, and in some such instances the side walls have collapsed and blocked up the passages. (_d_) Almost every passage appears to have originally been paved with blocks which were covered over with granite cement, but the cement, except in a few instances, has decomposed and been washed away by centuries of rains, though abundant traces of it remain. (_e_) Sunken passages built very much below the levels of the ancient floors on either side of them are numerous. The best instances of sunken passages are the North-East Passage between the Elliptical Temple and the Valley of Ruins, also the North-West Ascent to the Acropolis (upper portion), and the sunken passage in the Eastern Temple on the Acropolis.