great number of graceful fragments of mediæval work to be found within the narrow streets of Segni. The town has most likely been for ages too poor to follow the example of its richer neighbours in replacing beauty by ugliness. But he will do better to keep for a while from entering the inhabited part of the town. Let him first make the circuit of the ancient walls. And he can hardly doubt whether to turn to the right hand or to the left. The claims of the left are in this case overwhelming. Long before he has reached the town, he must have seen far away on the hill the most precious of the remains of Signia, the gateway which stands, forsaken but still untouched, beckoning him, as it were, to make his way first of all to the most instructive thing which the primæval city has to show him. But before he can reach either the Roman or the primæval gate he will have begun to notice the character of the wall. The construction is hardly so rude as the rudest parts of the wall at Cori, but a great deal of it belongs to the same general stage of engineering progress. The huge polygonal stones are heaped together; but one might note perhaps two stages, yet often intermingled--one, where the sides _only_ of the stones are cut so as to fit their neighbours; another, where the outer faces are also smoothed of what is called "rustication" in late _Renaissance_ work. In the first they are not left so utterly in a state of nature as they are at Cori. Their sides have been cut to the shape which was thought best for the work of piling them together. In a later stage, also seen at Cori, the outer sides, those which stand free from the scarped wall, are also cut; but it is not always easy to say how much of the change of the surface is due to art and how much to weather. At Segni the peculiar shape of the enclosure makes it somewhat hard to follow the line of the walls without a ground-plan, and a ground-plan is not to be had at Segni merely by asking for it. But it is plain that, in many parts at least, on the whole side of the hill which lies exposed to the open valley, and on the head of the whole promontory, there was, whenever the ground allowed and required it, a double wall, one on the edge of the hill, the other at some distance down its side. The most famous of the gates of Segni, locally known as _Porta Saracenesca_, leads from the outside world into the outer enclosure, at a point well chosen for military purposes, close to the edge, and commanding the path by which the traveller will most likely make his way to it. And a mighty gate it is, and one that holds no small place in the history of the art of construction. It is one of those instances which show that their builders were still ignorant of the principle of the arch, but that they were, so to speak, in search of it. They had not yet learned how to make the top of an opening out of stones really so arranged as to stand by mutual support; but they