OLDCASTLE, a market-town and post-town, and a parish, in the barony of DEMIFORE, county of MEATH, and province of LEINSTER, 20 miles (N. W.) from Trim, and 45¾ (N. W.) from Dublin, on the road to Killesandra; containing 4718 inhabitants, of which number, 1531 are in the town. The name of this place is supposed to be derived from the ruins of a castle, of which, however, not a vestige can be traced. The town occupies about 6 acres, and contains 241 houses. The market- house, in the centre of the town, is a handsome oblong building, affording accommodations for the market below, and for the petty sessions above; here is a dispensary. The largest market in the county is held here, every Monday, for yarn, particularly the finer kinds; and it is also plentifully supplied with pigs, meal, potatoes, butter, butchers' meat, &c. There are three principal fairs, on the 2nd Monday in June, Aug. 20th, and Oct. 28th; and some minor fairs have been lately established, for cattle, sheep, horses, pigs, yarn, butter, and wool. Petty sessions are held on alternate Mondays. The parish, also called Clolyne, comprises 7559 statute acres, as applotted under the tithe act, and valued at £1, 10. per acre. Agriculture is in a prosperous state; about half the land is under tillage, and the other half is pasture; the supply of peat is abundant. There are several fine quarries of limestone, which is carried to a great distance, in the county of Cavan, for burning into lime. Extensive flour and oatmeal mills, at Millbrook, were erected, in 1777, by John Henry, Esq., on his estate, which consists of 200 acres; the establishment is conducted by his grandson, W. Henry, Esq.; they have the convenience of a sixty-horse power by water supplied from Lough Crew; the concern employs 50 hands: the mansion, on an eminence, commands extensive views of the surrounding country; and here the river Inny takes its rise. "Newcastle is the residence of T. Battersby, Esq.; Millbrook House, of W. Henry, Esq.; and the glebe-house, of the Rev. N. J. Halpin. The living is a vicarage, in the diocese of Meath, and in the patronage of Lord Dunsany: previous to the demise of the late incumbent, it was united to the rectory of Castlecorr, otherwise Kilbride, but is now a separate benefice: the rectory is impropriate in the Marquess of Westmeath. The tithes amount to £415. 19. 11., of which £184. 16. 8½. is payable to the impropriator and the residue to the vicar. The glebe-house was erected at an expense of £738, of which £277 was a gift, and £461 a loan from the late Board of First Fruits: the glebe comprises six acres, valued at £12 per ann., but subject to a small quit-rent. The church is a plain substantial building, "with a tower and spire, in very good repair; it was rebuilt by a loan of £1000 from the same Board, in 1816, and the Ecclesiastical Commissioners have recently granted £284 for its repair: the spire was erected at the expense of J. L. W. Naper, Esq., of Loughcrew, lord of the manor. In the R. C. divisions the parish is the head of a union or district, comprising also those of Loughcrew and Moylough, in which union are two chapels; that of Oldcastle is a large plain building, erected in 1815, at an expense of £2000, on a site given by J. L. W. Naper, Esq., who also contributed £1000 towards the building. The altar-piece is by Craig, a native of this parish; it is copied from the original by Angelo, and represents the Taking down from the Cross. There is a neat chapel for the Primitive Wesleyan Methodists, "who are in strict communion with the Established Church. Here is a large school upon the Lancasterian principle, established by the late Lawrence Gibson, Esq., a native of the parish, who realised a large fortune in London, which, he left to endow a male and female school: the school-house is a very handsome building, erected at the cost of £6000, and capable of accommodating 1000 children; the average attendance being 800. It stands upon an enclosed space, containing 2 acres, divided into gardens and shrubberies, and a play-ground: the land was the gift of J. L. W. Naper, Esq.: the annual income of this foundation, from debentures in the three and a half per cents, is £S00. There are also five private schools, in which are about 150 children; and a Sunday school.