Down in the town below, the loyalists and nationalists of Northern Ireland confront, abuse and fight each other, and the police, in an atmosphere of simmering menace and venom.
Yesterday, on the Garvaghy Road lay the latest remains of the street battles which began after the murder of solicitor Rosemary Nelson - shattered bottles used for petrol bombs, pieces of paving stones, charred tarmac, a fire-damaged chip shop and, in front of the business centre, the twisted skeleton of the bus which had been hijacked and set alight.
Portadown is a place where they do not forget or forgive. It is the constituency of David Trimble, but it is also the place where Billy Wright organised and led the Loyalist Volunteer Force, and Rosemary Nelson worked with the Garvaghy Road Residents' Association.
Here on the council estates few have doubts as to who was responsible for the car bomb which blew up Ms Nelson.
"It was the RUC," said Jimmy Halloran, matter-of-factly. "They may have used some loyalist thugs, but they did it. They have done things like this before, and still continue. The peace process means nothing here - this is Portadown."
At the local community centre they talk about how loyalist crowds baited Catholics with chants of "Rosemary No-Legs" within hours of her death. Then, they say, on Wednesday, St Patrick's Day evening, protestants were " bussed in" by police to a nearby Orange hall where they strutted about beating their giant drums and hurling abuse about the "Fenian bitch" Rosemary.
Two councillors, Joe Duffy, and Brendan MacCionnath, say they went in to intercede with the police and were attacked. Yesterday, both had injuries to their faces and Mr Duffy a bruised arm.
Mr Duffy said: "If I hadn't raised my arm to protect my face it would have been far worse. We were trying to speak to the senior officers in charge. We were trying to prevent a riot and the police were hell bent on confrontation."
Mr MacCionnath is scathing about the plan to ask Kent police to investigate Ms Nelson's death. "She was being threatened by he RUC, and now another part of the same system will carry out the investigation.
"What we need now is an independent investigation involving the UN."
A few hundred yards from the Garvaghy Road stands Drumcree church. A group of Orangemen have maintained a vigil since last summer.
Here, they feel angry that in a town where Protestants make up 73 per cent of the population, they are being denied the legal right to march.
"It was the nationalists who have been doing the rioting," said David Jones, of the Portadown Orange Lodge
"It was they who burnt buses and petrol-bombed the police. Of course there has been a lot of violence in Portadown... but it has been nationalists attacking our legal parades.
"If we are repeatedly snubbed then a different type of loyalist will take control and we may end up with more Rosemary Nelsons."
The different type of loyalists are the ones who still have a presence in the Protestant estates which are the strongholds of the LVF. The organisation says it is holding the ceasefire, but security sources say elements from it have almost certainly been involved in sectarian attacks.
In Belfast and Londonderry the murals are changing on the walls from martial to more social ones. But they are not returning in Portadown where fresh pictures of balaclaved men with guns go up regularly.