A view that is no longer private property

The Black Mountain looms over Belfast, but until this month the city's people were banned from enjoy

The man stands at the peak of the Black Mountain and his eyes scavenge the startling Mediterranean blue of the sky above Belfast. "Where is the little bastard?" he murmurs. "Ah, there he is. Now isn't that lovely?"

He's spotted a skylark. The soundscape is silence and skylarks and meadow pipits and his feet on heath and heather and lush, black bog. It is the beginning of June 2005, and before the month is out the Black Mountain will be open for the first time to the people.

Terry Enright slowly turns 360 degrees. "I've never seen this before," he says. "It's never been so clear." What he sees is Scotland far over to the east, and the Isle of Man, and when he turns inland there is Lough Neagh - the biggest lake in these islands - five of the Six Counties and Donegal on the west coast. Down below is the bowl of Belfast. "The people of Belfast never saw this. They live here but it's not been part of their life." Enright lives here, too, on a Ballymurphy council estate nesting at the bottom of the mountain that skirts the city skyline. But he made it his mission to move around the mountain.

There is still a blue notice where the road meets the path to the peak, telling people to keep out of private property. Actually, it isn't private; since the 1980s the cap of the Black Mountain has belonged to the Ministry of Defence, and before that to farmers. "I was once up here on my own looking for an old ruin of a building, and jeeps skidded to a halt. The soldiers all spread out and headed towards me and asked me what I was doing. I said, 'You're not going to believe me. I'm looking for a ruin.'" When yet another squad challenged him during another dander, says Enright: "I said, 'What are you doing here? I fucking live here, brother.' Anyway, I gave the soldier a leaflet about the mountain, and I said: 'Here, send that to your mammy and show her where you are.'"

Where he was happens to be one of the most exhilarating transitions between town and country. Terry and Mary Enright, activists much loved in Belfast, look up from their Dermott Hill front door to a place more than a thousand feet high, and they can be up there in minutes.

John Gray is the distinguished guardian of Belfast's Linen Hall Library - itself an ingenious tribute to the creativity that can come from conflict - and lives in north Belfast. Minutes from his front door he, too, can rise a thousand feet above the city. "The nearest equivalent is Arthur's Seat [in Edinburgh] - and that's small," Gray says. "It doesn't have a 300-foot promontory, it doesn't have a prehistoric fort . . ." His list goes on. "It's an extraordinary place, and it is one of the principal ways I stay sane. I go up in blizzards, I go up at moonlight, I go up on a clear day when you can see as far as the Scottish Highlands, or the English Lake District. It is unlike anywhere else in Britain - a mountain projecting straight into an urban environment. It is a unique transition." Gray recalls that in another era, the mountain used to infuse the childhood narratives of Belfast's citizens. "It was a place of escape and adventure."

That was before the Troubles. The Belfast Hills - Divis, White Mountain, Cave Hill and the Black Mountain - became not so much a war zone, as a zone emptied of the people down below. That leaflet given by Terry Enright to the soldier explained that there was a great movement to rescue the Black Mountain, both from the military and from quarry and construction companies.

Gray reckons Enright is the man of the mountain, "an inspiring person who emerged from a society that during 30 years of conflict had to find its own ways of doing things - some of those ways weren't for the best, some were". Republican west Belfast generates community activists who improvise ways of doing business. "He's an exemplar," says Gray. "He's an urban man, but he loves the mountain."

In a political context "dominated by the orange and the green", a context still "substantially dysfunctional", according to Gray, Enright is also known as an artful coalition-builder who brings working-class class to environmentalism. Since 1990, when he became outraged by the quarrying that was gorging on the mountain and then stuffing the holes with waste, Enright has enlisted people from both posh civic-heritage campaigns and hard Catholic and Protestant estates to "walk the walk".

"We took people up the mountain to motivate them," he says. If they could discover the evidence of ancient habitation, its cairns, springs and flowers, they would want to love it and save it. The idea worked. Every August, during the West Belfast Festival, a coalition of community and conservation groups organises hundreds of people to walk the walk. At the edge of Enright's estate there is a mural painted by local children proclaiming: "Stop the destruction of the Black Mountain . . . for the land has been here longer than the likes of you."

Then, following the Good Friday Agreement, the MoD's "private property" was bought by the National Trust. Together with Belfast Hills Partnership, the trust will act as steward to the mountain. Already, environmentally friendly paths have been laid across the cap of the Black Mountain, before it finally opens to the public this summer; and "difficult" children being educated out of school have removed 1,500 discarded vehicle tyres from it.

But nothing has yet stopped the quarrying of the 80-million-year-old hard basalt lava out of which the mountain is formed, or the dumping of waste into the canyons this leaves behind. And over on White Mountain, a revolt is brewing in Castlerobin, a hamlet squeezed between the sites of two "superdumps" used by quarry companies to bury most of Northern Ireland's waste. Apart from the hazard to the mountain and its people, this practice now requires the evacuation of a colony of newts that have made the quarry their home.

"Angela Smith was the English minister sent in because our government is not up and running," says Margaret McCroskery, a Castlerobin resident. As environment minister for Northern Ireland, Smith gave planning permission for the dumps. But, says McCroskery, "People here are kicking up: our right to express an opinion in an inquiry has been violated; our community has no right of appeal."

The case signifies new expectations of politics created by the peace process, and a sense that in new times the Belfast Hills must move on to the political radar. They may have been there for 55 million years, but they are neither above nor beyond trouble.

Terry Enright looks from the road down to Belfast, back over the Black Mountain. There's a sprig of stones on the horizon, a cairn created by dispossessed kids in Belfast in memory of his son, Terry Og (young Terry), a gifted Gaelic footballer and a cross-community youth worker. He was shot during the spree of loyalist killings that preceded the Good Friday Agreement.

Terry Og's young widow, Deirdre, and her uncle, Gerry Adams, the Sinn Fein president, were among the pall-bearers that ugly, bleak day in January when 10,000 people - including a posse of Shankill teenagers - joined the dead man's cortege. Suddenly, the rain stopped and the sun shone. There was a noisy hush: a rainbow leaned across the city to the Black Mountain.