Mount Stewart is a 19th-century house and garden in County Down, Northern Ireland, owned by the National Trust. Situated on the east shore of Strangford Lough, a few miles outside the town of Newtownards and near Greyabbey, it was the Irish seat of the Stewart family, Marquesses of Londonderry. Prominently associated with the 2nd Marquess, Robert Stewart, Viscount Castlereagh, Britain's Foreign Secretary at the Congress of Vienna and with the 7th Marquess, Charles Vane-Tempest-Stewart, the former Air Minister who at Mount Stewart attempted private diplomacy with Hitler's Germany, the house and its contents reflect the history of the family's leading role in social and political life in Britain and Ireland.

Newtownards is a town in County Down, Northern Ireland. It lies at the most northern tip of Strangford Lough, 10 miles (16 km) east of Belfast, on the Ards Peninsula. It is in the civil parish of Newtownards and the historic baronies of Ards Lower and Castlereagh Lower. Newtownards is in the Ards and North Down Borough. The population was 29,677 in the 2021 Census.