Coordinates: 54°20′46″N 6°30′54″W / 54.346°N 6.515°W
Gosford Castle is situated in Gosford, a townland of Markethill, County Armagh, Northern Ireland, close to the border with County Down. Construction of the castle began in 1819 and finished in the 1850s. It was commissioned by Archibald Acheson, 2nd Earl of Gosford and the architect was Thomas Hopper, one of the leading London architects of the first half of the 19th century. It is the largest Grade A listed building in Northern Ireland.
The Ministry of Agriculture bought the estate in 1958, establishing Gosford Forest Park. In January 2006 the decaying castle was bought by a development company, the Boyd Partnership, which planned to turn it into private homes. In January 2008 the first residents of the new apartments moved in. The estimated repair bill was in the region of £4m, the nature of the development was selected by a government-appointed panel.
The style of Gosford is that of Norman revival, it being one of the few examples of this in the world. It was regarded by Robin Fredden, Secretary of the National Trust in 1952 as "one of the most original buildings of the first half of the nineteenth century", he further noted that it was "reputed to be the largest pile in Ireland", having some 150 rooms. Thomas Hopper, the architect, also designed Penrhyn Castle in Wales, which is in a similar style.