IT WAS always inevitable that the tower blocks of Ballymun would face demolition sooner or later. In many ways, they represent the classic example of unsustainable development, a mega housing scheme which ended up having a shelf life of less than three decades.

Like high-rise blocks all over Europe - indeed, right around the world - Ballymun was an aberration in the history of housing. It was based on the idea that living accommodation could be provided more quickly and cheaply by pre-fabricated system building than the tried and tested methods developed over centuries.

In hindsight, it is easy to see how Neil Blaney was so beguiled by the system building industry. It was all the rage in the 1960s, almost the Zeitgeist of the modern age, and he decided to employ the technique to create Ireland's first and largest high-rise estate, in an effort to solve Dublin's pressing housing problems.

That the idea was seen at the time as heroic is evident from the fact that, in 1966 - on the 50th anniversary of the Easter Rising - it was decided to name the seven tower blocks -in honour of the men who had signed the 1916 Proclamation.

It may not have been the "shining city on the hill", but it came pretty close to it. For Dublin Corporation's tenants, Ballymun was the place to be - and they were almost literally queuing up to get into "Ireland's greatest housing scheme" even before its completion in December 1968 was marked by a "simple and stirring" ceremony.

Built by the Cubitt-Haden-Sisk consortium, Ballymun consists of 3,068 dwelling units - 2,616 in system-built blocks, of four to 15 storeys, and a further 452 in two-storey terraces. It was built in just four years, using the French Balency system, with the pre-cast units manufactured in a plant on the site.

SEVEN months before it was finished, the system building industry had been rocked to its foundations by a gas explosion which caused Ronan Point, one of London's numerous tower blocks, to collapse like a house of cards. Within a few years, both the British and French governments had decided that there would be no more high-rise housing.

Problems were becoming evident in Ballymun, too. The provision of all sorts of amenities was supposed to go hand-in-hand with the housing, but this did not happen. For example, the original plan for the town centre included not just shops, but also a swimming pool, dance hall, bowling alley, restaurant, creche, clinic and Garda station.

As built, the "town centre was grimly functional, a "dull, inhuman place without any focal points or features", as Plan magazine described it at the time. The wide open spaces which had been one of the "selling points" turned out to be bleak, windswept communal areas which nobody looked after.

Lifts in the tower blocks were often out of order, forcing young mothers with young children to climb endless concrete stairways to reach their high-rise flats. In one 12-month period in the late 1970s, the corporation had to deal with 2,425 complaints about lift failures.

Although individual flats were quite commodious, many residents complained about rubbish-strewn external spaces and graffiti-scarred stairwells and landings as well as the isolation of living at high levels. The district heating system generated its own problems because people had no control over the temperature.

As the Architects Journal put it in 1974, tower blocks were a "disastrous" solution for social housing. "Gardens in the air and parks on the ground were a seductive vision; but the excessive costs of multi-storey housing forced local authorities to renege on the provision of basic amenities and communal facilities."

Just six years after Ballymun was built, "minor fractures" started to appear in the wall panels of the tower blocks - a problem caused by the use of quick-drying high-alumina cement. By 1979, exterior plaster around the 10,000 windows began falling away and had to be patched up with patent mortar.

SIMILAR difficulties had plagued high-rise developments in Britain, and the combination of soaring repair bills and increasing vandalism made demolition a realistic option. In several cases, flats built in the 1960s were dynamited to dust; one of these demolitions, in 1979, was attended by Dublin Corporation's chief housing maintenance officer.

By the mid-1980s, Ballymun had become a sociological "sink". Unemployment was estimated at 45 per cent, at least 1,000 tenants were drug addicts, one in six were single mothers, a further 10 per cent were either deserted or separated wives, and Ballymun was declared the State's "most disadvantaged area".

Whatever about dealing with its social problems, something had to be done about the physical condition of the estate. In 1993, one of the seven 15-storey towers and two of the 19 eight-storey spine blocks were refurbished at a cost of £6.7 million. But the most recent estimate for refurbishing the whole estate came to £144 million.

This figure was so staggering that demolition and complete rebuilding to a new plan became a realistic option. The cost of the scheme sanctioned yesterday by the Government would amount to £179 million, or £35 million more than an overall refurbishment.

Not surprisingly, there was resistance right up until the last minute from the Department of Finance. But the Taoiseach, Mr Bruton, and the Tanaiste, Mr Spring, both visited Ballymun within the past few weeks and their support proved crucial in winning Government support for the demolition option.

The Minister for the Environment, Mr Howlin, is naturally delighted that his much-prized Millennium project has now been sanctioned by his Cabinet colleagues. He went to Ballymun yesterday afternoon to tell people the good news, and it was greeted by local community leaders uncorking at least one bottle of champagne.

"This is not simply a housing issue," he told The Irish Times. "It's also about the social and economic regeneration of the area. And what I'll be doing now is pulling together the Corporation, the Ballymun Task Force and the various State agencies to draw up a strategic plan for the whole estate by the end of this year."

Describing it as "the most important piece of urban regeneration in 30 years", he said there would be design competitions for various "modules" of the new estate as well as scope for private sector involvement. And the avowed intention is to transform Ballymun into a "model town for the 21st century".