The park consists of 194 acres of rolling pastureland, mixed woodland and gardens, overlooking the bay of Drogheda. Ardgillan, meaning high-wooded area, is a sanctuary for many species of mammals and birds.
The ground floor rooms of the castle, accessible to wheelchair users, are furnished in Georgian/Victorian style and include the Morning Room, Dining Room and Library.
The first floor area of the castle is used for an annual programme of exhibitions, while Ardgillan is also the home of a permanent exhibition of maps including the 17th century 'Down Survey of Ireland'.
Facilities inlude, tea rooms within the castle, picnic area, rose garden, Victorian conservatory and a walled kitchen garden.