Even Rome, to the age of Nero, was crowded, unwholesome, and mean, over a great portion of its less important surface. In one respect, however, it seems to have differed greatly from every other ancient city of which we read, namely, in the great elevation of the houses; in almost every other instance we are led to an opposite inference, which is further corroborated by the present appearance of Pompeii. With the _Domestic Architecture_ of the primitive ages, to which our accounts have hitherto been confined, the acquaintance to be obtained is exceedingly limited. In the description of Solomon's Palace, and in various passages of Homer, considerable details are given of the palatial dwellings; but how the greater part of mankind were lodged, few means of determining remain. Protection against the vicissitudes of climate would first employ the instinctive ingenuity of man; next, conveniency would be consulted, by enlarging the dimensions of his abode. Both these objects might be obtained, while yet the original circular area was retained. As some ideas, however, of the comforts and decencies of life prevailed, seclusion of the different orders and sexes in the members of the family would be sought; and hence division of one common apartment into separate portions. But as circular space admits of division very imperfectly, and with loss, this new necessity would introduce, or at least render permanent, the rectangular shape of the domestic abode. _Military Architecture_ is but little connected with the history of the science, from the peculiar nature of those principles of construction which it recognises. Here design is regulated by circumstances external to the art, and which, therefore, though enriched by novel combinations in its later and more impure modes, received originally no component elements, from a branch which has universally and largely engrossed the attention of mankind. The application of architecture to the purposes of defence, would not take place till a comparatively later period in the history of the species. Men would previously have acquired ideas of the right and value of property, and divided into separate communities by political or moral distinctions. Mere defence would be the first object in military erections; a wall, a rampart, or barrier, of altitude and strength sufficient to resist, or rather to disappoint, any sudden attack, would be all for some time required; and, subsequently, with facility of access to the summit, for the purpose of hurling stones from vantage ground upon the assailants, these defences for long would be complete, by the obvious addition of a ditch. As the arts of violence, and especially as missile warfare improved, experience would point out the impossibility of defending, even with a ditch, a long unbroken line of wall, consistently with the safety of the defenders, who, in the attempt to overlook the whole, would necessarily be exposed to the hostile weapons. To obviate this