Hillsborough Castle is an official government residence in Northern Ireland. It is the residence of the Secretary of State for Northern Ireland and the official residence in Northern Ireland of Queen Elizabeth II and other members of the British Royal Family when they visit the region, as well as a guest house for prominent international visitors. Hillsborough Castle, which is located in the village of Hillsborough in northwest County Down, is not a true castle. It is a Georgian country house built in the 18th century for the Hill family, Marquesses of Downshire, who owned it until 1922, when the 6th Marquess sold the mansion and its grounds to the British government. Hillsborough Castle became the controversial location of the signing of the Anglo-Irish Agreement in 1985. In addition to this, many of the crucial talks leading up to the signing of the Good Friday Agreement in 1998 took place in the secretariat attached to the castle. Mo Mowlam broke new ground when she opened the extensive grounds of the castle to the public