Mount Stewart is a 19th-century house and garden in County Down, Northern Ireland, owned by the National Trust. It was the Irish seat of the Stewart family, Marquesses of Londonderry, with ties to prominent figures like Viscount Castlereagh and the 7th Marquess of Londonderry. The house reflects the family's history in social and political life in Britain and Ireland. The property has a rich past, including being briefly occupied by United Irish insurgents in 1798. Today, it stands as a historic residence open to visitors, showcasing its grand architecture and beautiful gardens overlooking Strangford Lough.