This castle is situated on the banks of the Foyle where it narrows inland, somewhat over a mile south of Saint Johnstown and seven miles from the City of Londonderry.

Only the keep now remains, but during the last century the walls of the courtyard which lay between the Foyle and the fortress were still standing, and over the arch of the gateway was a small stone engraved with the initials “I.S.E.S.T.” and the date 1619. This has, however, now disappeared. Another inscribed stone bears the following: “The Hon. Elizabeth Hamilton, daughter of John Lord Culpeper, and widow of Colonel James Hamilton (who lost his life at sea in Spain, in the service of his king and country), purchased this manor, and annexed it to the opposite estate of the family, which paternal estate itself has improved by her prudent management to nearly the yearly income of the dower she received thereout. She has also settled her younger son, William Hamilton, Esq., in an estate acquired in England, of nearly equal value in the purchase to this, and given every one of her numerous offspring, descended from both branches, some considerable mark of her parental care. Her eldest son, James, Earl of Abercorn, and Viscount Strabane, hath caused this inscription to be placed here for the information of her posterity, Anno, 1704.”

There are two incidents in the castle’s history which are of particular interest. In the sixteenth century it was the chief residence of the beautiful “Ineen Dubh,” daughter of Macdonnell, Lord of the Isles, and mother of the famous Red Hugh O’Donnell, Chief of Tyrconnell.

It was said of her that she was “excelling in all the qualities that become a woman, yet possessing the heart of a hero, and the soul of a soldier.”

The State Paper recording her possession is as follows: “From Cul-Mac-Tryan runs a bogg three myles in length to the side of Lough Foyle—in the midst of the bog is a standing loughe called Bunaber—here at Bunaber dwells O’Donnell’s mother (Ineen Dubh M’Donnell). Three miles above Cargan stands a fort called McGevyvelin (Mongivlin) upon the river of Lough Foyle—O’Donnell’s mother’s chief house.”

The fortress is mentioned in 1619 in Captain Pynnar’s Survey of the Escheated Counties of Ulster in the following manner: “Sir John Stewart hath 3,000 acres called Cashell Hetin and Littergull. Upon this proportion there is built, at Magevlin, a very strong castle, with a flanker at each corner.”

James II. was the guest of Archdeacon Hamilton at Mongevlin during the siege of Derry. From there he sent proposals of surrender to the garrison by his host, which were rejected.

A sad incident occurred in connection with the castle last century. A servant lad being employed by the owner of the time was so terrified by the ghost stories he heard in connection with the building that he left his situation and went home. His friends persuaded him to return, but the matter so preyed upon his mind that he shortly after hanged himself.