TRE’R CEIRI.—Across a hollow, from one summit of the Rivals (Eifl) to the other, extends an immense rampart of stones, or perhaps the ruins of a wall, which effectually block up the pass; and near this place, on the summit of these hills, is a most perfect and regularly fortified British Post, called Tre’r Caerau, the Town of Fortresses, or perhaps Tre’r Ceiri, the Town of the Giants. The most accessible side is defended by three walls; the lowest is very imperfect, the next tolerably entire, and has in it the grand entrance; this wall, in one part, points upwards towards the third, and runs round the edges of the top of the hill; the second wall unites with the first, which runs into a point, reverts and joins the highest, in a place where the hill becomes inaccessible: the facing on the two upper walls are very entire, especially that of the uppermost; they are lofty, and exhibit from below a grand and extensive front; the space on the top is an irregular area, part is steep and part flat, and is covered with heath, which affords shelter to a few red grouse;—the whole is almost filled with cells.—To be seen with advantage, the station should be taken from the summit, about which the cells (which are the foundations of the huts of the soldiers,) are very distinct, and disposed with much art: about the middle is a square place, fenced with stores, a sort of _Prætorium_, surrounded with two rows of cells; numbers are also scattered about the plain, and others again are contiguous to the wall, all along the inside. The fortifications on Pen-maen-mawr bear a great similarity to the mode of defence adopted on this strong Post. The cells are mostly perfect, of various forms, round, oval, oblong, and square; some of the round are fifteen feet in diameter, of the oblong, thirty feet in length, with long entrances, regularly faced with stone; all of them, when inhabited, were no doubt well protected from the weather, by roofs covered with thatch and sod. The upper wall was in many places fifteen feet high on the outside, and often sixteen feet broad; it consisted of two parallel and contiguous parts, one higher than the other, serving as a parapet to the lower, which seemed to have its walk, like that at Chester; there was in one place a cell in the thickness of the wall, or perhaps a sally port, in part stopped by the falling in of the stones. There is an excellent plan of this encampment in Mr. Pennant’s Tour. We shall now descend from these elevated summits, in order to visit Nant Gwrtheyrn, or Vortigern’s Valley, where that Prince is said to have fled from the rage of his subjects, and where it was said he and his Castle were consumed with lightning. His life had been profligate, the Monks therefore were determined that he should not die the common death of all men, and accordingly made him perish with signal marks of the vengeance of Heaven. Fancy cannot frame a place more