The first one went up eight years after construction started on the Berlin Wall, but 20 years after that wall went down, Northern Ireland still has its so-called peace lines.
For people living in the shadow of a concrete wall topped with fencing the peace they bring can help cement divisions rather than heal communities.
Wall number one, which divides the Falls and Shankill roads at Cupar Street, went up in 1969 following rioting and house burnings in west Belfast. Over the years it has risen to more than six metres.
The last one went up last year in the grounds of a north Belfast integrated primary school following a period of local tension.
There are 53 Northern Ireland Office maintained peace lines in four towns and cities in the region - 42 in Belfast, five in Londonderry, five in Portadown and one in Lurgan.
However, community relations groups say these are not the only peace lines, with other structures and land being used to keep communities apart.
In a survey for the Community Relations Council the Institute for Conflict Research listed a total of 88 peace lines as well as 44 police CCTV cameras.
Some are listed as wasteland being used by housing authorities as buffer zones, others include derelict houses as well as walls and vegetation to the rear of homes in interface areas.
They still make some people feel safe, but others want more work on taking them down.
Tony Macauley used to live under the Shankill peace line and last year he produced a consultancy paper on a process to remove them.
He said that while they initially made him feel safe he quickly realised that they did not stop people crossing over to carry out killings.
He now lives in a seaside town and said that for younger people in interface areas the peace lines have become part of the fabric of their area, as accepted as the murals that adorn gable walls.
"I can remember when the peace walls went up, but there is an entire generation who have known nothing else," he said.
"People who grew up in some of those areas and are under 40 have no idea what it was like before them.
"But they used to be mixed areas, the communities used to live side by side."
The CRC lists some of the peace lines as fences around enclaves and swathes of scrub used as buffers in interface areas.
Others cannot be mapped, as Mr Macauley explained.
"It happens in urban areas, but also in rural ones, where people know they should avoid a certain route to get somewhere or there would be some park they would not go to," he said.
He said that until communities could agree to live without them the walls would have to stay, but his hope is that talking about removing them will eventually lead to them going.
It takes an outsider to be shocked by the sight of the a peace wall and what it is - a means to stop people living in a western democracy at the start of the 21st century attacking each other.
But even on the walls change can be seen. Murals and graffiti art expressing hopes for peace and a brighter future feature on the Belfast wall now.
Photographer Les McLean is a regular visitor to Belfast and has been capturing its people for years.
He said that the peace murals and messages that have been appearing on the walls have helped soften their harsh look, but there is no disguising what they are.
"I like what they are saying now - the message that's coming out of there," he said.
"I've been photographing them for the last two or three years and I have always felt I couldn't understand why they were called a peace line, I've always thought they were more about division," he said.