An Bord Pleanála has upheld a decision of Meath County Council to grant planning permission for almost 600 homes at Dunboyne Castle demesne.
The board rejected the recommendation of its planning inspector by granting permission for the development, which includes demolition of part of the castle and the creation of a 121-bedroom hotel and leisure centre. Dunboyne Castle, its gates and stables, which are the subject of protection orders, was sold for €23 million by the Keating family three years ago.
The new owner was well known in the Dublin house-building firm Menolly Homes.
The same year, the castle and demesne lands were made the subject of an Integrated Area Action Plan providing residential and other mixed use development in the 2001 Meath County Development Plan.
The council's decision to rezone the 65 acres from tourist amenity and recreational uses to residential units had raised the concern of locals. The subsequent planning application was opposed by 16 local groups and individuals.
Planning permission for the redevelopment was granted by Meath County Council last September.
Menolly Homes now plans to convert Dunboyne Castle to a hotel on a 20-acre portion of the site. This would involve the removal of a two-storey east wing and single-storey west wing extensions and the addition of a 121-bedroom extension.
The existing two-storey stable building is to be renovated and converted into 10 apartments. The hotel is to include conference and business meeting facilities, a banqueting hall, gym and leisure centre with a spa and treatment rooms and an 18-metre swimming pool.
The company has said the grounds of the hotel will be open to locals. It has also "expressed its willingness" to upgrade the town park. which it describes as "under-utilised and derelict" and incorporate riverside walks and cycle paths through the development.
The residential element will be on 47 acres of the site - a mix of 344 detached, semi-detached and terraced houses and 220 apartments in 11 blocks. The remainder of the site - 23 acres - will be allocated for community, recreational and educational use.
Dunboyne Castle lies to the south west of Dunboyne village adjoining the Castle River.