CAERLEON, a market-town in the parish of HLANGATTOCK, lower division of the hundred of USK, county of MONMOUTH, 20 miles (S. W.) from Mon- mouth and 151 (W.) from London, containing 1062 inhabitants. This place, called by the Britons Caer- lean, city of the legion, or, according to some, Caerllian, city of the waters, was the Isca Silurum of the Romans, in the time of Claudius, whose second legion, being recalled from Germany, was stationed here under the command of Vespasian. It became the metropolis of that division of the island called Britannia Secunda, and one of the chief cities of the Romans, who fortified it with strong walls three miles in circuit, enclosing a quadrilateral area, measuring five hundred and thirty yards by four Irandred and sixty: they erected temples, an amphitheatre, baths, aqueducts, and splendid dwellings of various descriptions, the magnificent remains of which, in the twelfth century, are described by Giraldus Cambrensis as emulating the grandeur of Rome itself. In the reign of Domitian, St. Julian and St. Aaron, both of whom preached the doctrine of Christianity in this part of Britain, suffered martyrdom at this place; but after the final submission of the- Britons to the Roman power, Caerleon became, under the auspices of Antoninus, the seat of learning and devotion. Three Christian churches were erected, two in honour of the martyrs St. Julian and St. Aaron, to which a nunnery and a pjriory of Cistercian canons were annexed respectively; and a third, to which was added a monastery that afterwards became the metropolitan see of Wales, and of .which Dubricius, the great opponent of the Pelagian heresy, was the first archbishop. Under his successors the see continued to flourish to such an extent, that, at the time of the Saxon invasion, its college is said to have contained, among other students, not less than two hundred who were well skilled in geography and astronomy; it was afterwards translated to Menevia by St. David, and has since that time been known as the see of St. David's: thereare some small remain's of the monastery still existing. The castle was probably built about the time of the. Conquest, but no mention of it occurs till the year 1171, when Henry II, took the town, and deposed lorwith ap Owen, lord of Gwent, who, in 1173, retook it after a vigorous defence, and restored it to the Welch. After repeated sieges it was retained by Llewellyn ap lorwith till the reign of Edward I., when, upon the overthrow of the independence of the Welch, the town fell into neglect, and the castle into decay: the reihains of the castle are inconsiderable, consisting chiefly of heaps of stones round the base of the lofty mount on which the keep was built, and the ruins of a dilapidated portal at a distance, that probably formed the entrance. The town is pleasantly situated on a gentle acclivity on the bank of the river Usk, over which is a handsome stone bridge of modern structure, and consists of two streets indifferently paved and lighted; the houses are mostly old and irregularly built, and are fast hastening to decay: some fragments of the ancient walls are still remaining, and bear testimony to the former extent and importance of the town, which has since dwindled into comparative insignificance. The trade consists principally in the manufacture and sale of tin-plates and iron, for which there are two large establishments; the articles are conveyed to Newport by. the river Usk, in vessels of small burden. The market is on Thursday: fairs are held on July 31st and October 2nd, the latter being a large fair for horses. The market-house is a dilapidated edifice, supported on four massive pillars of the Tuscan order, supposed to have belonged to some Roman structure, two bases of similar dimensions and character having been dug up near the walls. The county magistrates hold a petty session once a fortnight. There are places of worship for Baptists, Independents, and Wesleyan Methodists. The free school, for clothing and educating twenty-five boys and twenty-five girls, was founded and endowed, in 1724, by Charles Williams, Esq.; the master's salary is £75 per annum: there is an almshouse for aged widows, who.receive twenty shillings per annum each. Several remains of the Roman station are still 'visible, and numerous minor relics have been discovered, consisting of portions of columns, altars dedicated to Jupiter Dolichenus and the goddess Astraea, bricks inscribed " Leg. II. Aug.," tesselated pavements, coins from Csesar to Valentinian inclusive, earthen vessels, urns, a gold ring with an intaglio representing Hercules strangling the Nemsean lion, a cornelian seal of Ceres (found about twenty years since), a mutilated statue of Jupiter in bronze, portions of the baths, &c. To the north of the town is an extensive quadrilateral encampment, with seven smaller camps near it; and on the banks of the Usk are considerable remains of the amphitheatre, called by the inhabitants King Arthur's Round Table, St. Amphibalus, the tutor of the protomartyr St. Albanus; and the martyrs St. Julian and St. Aaron; were born in this place. The renowned King Artliur is stated to have been interred here.