Stormont Castle is a mansion in east Belfast which is used as the main meeting place of the Northern Ireland Executive. It was never a castle as such: the original building was reworked in the nineteenth century in the Scottish baronial style with features such as bartizans used for decorative purposes.
Between 1921 and 1972, it served as the official residence of the Prime Minister of Northern Ireland. However, a number of prime ministers chose to live at Stormont House, the official residence of the Speaker of the House of Commons of Northern Ireland, which was empty as a number of speakers had chosen to live in their own homes. It also served as the location of the Cabinet Room of the Government of Northern Ireland from 1921 to 1972.
Before devolution it served as the Belfast headquarters of the Secretary of State for Northern Ireland, Northern Ireland Office Ministers and supporting officials. During the Troubles, it was also used by MI5 officers.
The castle is open to the public each year on the European Heritage Open Day weekend.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.