For over 15 years the centre of Belfast was surrounded by a perimeter of 12 foot high fences, barbed wire and concrete.
Movement in and out was restricted and controlled by armed soldiers. All who entered were searched by specialist security staff.
This was a radical experiment in state-managed urban fortification, where new methods of security and surveillance were pioneered to create a unique city centre, one which has never been seen before or since in the UK and Ireland.
As the Northern Ireland conflict developed, the barriers, gates and fences separating the city centre from the rest of Belfast also changed to reflect the evolving security situation.
As the Troubles ended and peace became the new normality, the barriers slowly disappeared, leaving only shadows of their former presence.