It is allowed to have a prison for petty offences independent of the sheriff. Its burgesses likewise were exempt throughout the kingdom from tollage, lastage, passage, murage, pontage, and all other impositions of whatever kind, with other privileges, too numerous to insert. The county prison is likewise near the castle. It was erected in the year 1794. The new market-house, containing the butchers’ shambles, &c. is a well-contrived and convenient building, affording good storage for corn and other articles left unsold. The site of the ancient town of Segontium, which lies about half a mile south of the present one, will be found worthy the attention of the traveller; it was the only Roman station of note in this part of Cambria, on which a long chain of minor forts and posts were dependent. It is even maintained, and that by respectable authorities, that it was not only the residence but burial-place of Constantius, father of Constantine the Great; but most probably this arises from confusing Helena, the daughter of Octavius, Duke of Cornwall, who was born at Segontium, and married to Maximus, first cousin of Constantine, with Helena, his mother, whom these authorities assert to have been the daughter of a British king. A chapel, said to have been founded by Helen, and a well which bears her name, are amongst the ruins still pointed out. Since the numerous late improvements have been going forward at and near Caernarvon, new and interesting lights have been thrown on the ruins in its vicinity, which will form a rich treat to the antiquary. Near the banks of the Seint, from which Segontium took its name, and which runs from the lower lake of Llanberris, are the remains of a fort, which appears to have been calculated to cover a landing-place from the river at the time of high water: it is of an oblong shape, and includes an area of about an acre; one of the walls which is now standing is about seventy-four yards, and the other sixty-four yards long, in height from ten to twelve feet, and nearly six feet in thickness. The peculiar plan of the Roman masonry is here particularly discernible, exhibiting alternate layers, the one regular, the other zig-zag; on these their fluid mortar was poured, which insinuated itself into all the interstices, and set so strong as to form the whole into one solid mass; retaining its texture even to the present day, to such a degree, that the bricks and stone in the Roman walls yield as easy as the cement. English history has spoken so fully on this place, as connected with Edward the First, on the title, which he, from his son being born in this castle, so artfully claimed for him, and the future heirs apparent to the British throne, as affording to the Welsh a prince of their own, agreeable to their wishes, and the quiet annexation of the principality to his dominions, which Edward by this means obtained, that it appears superfluous to enlarge upon it in this work.