The new building in Dame Street beside City Hall may be the most detested addition to Dublin, writes Frank McDonald, Environment Editor

It was to be a landmark building, and it certainly is - but not in the way Dublin City Council might have hoped when the plans were first unveiled in 2001.

It was also to be a public building with a cultural use - a Revenue museum was intended - but instead it's the city's most peculiar spec-built office block.

The idea that lay behind it was a good one - to repair some of the damage caused by the roads engineers when they drew a line through an intact ensemble of Georgian buildings on Dame Street and Palace Street, just east of City Hall, with the aim of widening the main carriageway.

This was planned and executed in the 1970s at a time when the grim-reaper engineers regarded much of Dublin's older fabric as little more than an obstacle to traffic movement.

And their misguided thesis was endorsed by narrow-minded bureaucrats and ignorant councillors, despite heartfelt pleas by conservationists.

Had it not been for the late George Weekes, secretary of the Sick and Indigent Roomkeepers' Society - the city's oldest charity - its headquarters on Palace Street would also have been cleared into a skip. But although the building was spared, its party wall was left exposed, complete with blocked-up fireplaces.

After years lying derelict, with buddleia flourishing behind a slatted timber fence painted alternately blue and white, the leftover site was laid out as a "pocket park" in 1988, with fast-growing sycamores to cover up the scar, twin circular podiums of grass and three statues forlornly gathered around a pool and fountain.

Though quite popular in summertime, the "park" always looked like something of a stopgap measure, pending a more definitive response by the city administration. And this finally came in 1999 when city architect Jim Barrett commissioned David Mackay, of Barcelona architects MBM, to design a building for the site.

Mackay (73) was one of the "three wise men" engaged by Barrett to give independent advice on major schemes for the city, the others being Richard MacCormac and John Worthington. Through MBM, he also had a proven track record as a master planner - notably in laying out Barcelona's Olympic Village and harbour for 1992.

In his prologue for MBM's latest brochure, critic Deyan Sudjic describes them as "architects of sensitivity and discretion. They are not interested in creating aggressive or spectacular architectural objects, or signature buildings. Yet they make buildings with a distinctive flavour and warmth that clearly demonstrate their roots". To them, Sudjic writes, architecture is "about making places, about the manipulation of space, about the tactile quality of materials".

Through five decades of work, MBM had "remained focused on this definition", retaining and refreshing its creative energy to be "a powerful voice for a dignified vision of architecture and urbanism".

So how is that vision translated into the new building and public space beside City Hall? Not very well is the answer. Part of the problem is that the building itself seems cropped, to preserve views of the east elevation of City Hall, while the landscaped plaza is so hard that it is likely to set back "hard landscaping" for years.

A 1999 sketch in MBM's brochure shows that the original plan involved excavating the site to create an exhibition area beneath the plaza with a flush rooflight, billed as a "Window to Bloomsday room".

In this same drawing, the plaza itself is misnamed "12th of June Square", though everyone knows Bloomsday is on June 16th.

"This project stems from the idea of turning the space into a real, clearly defined square", according to the accompanying text.

"It is, then, a building with almost no functional programme; it is purely an urban design resource, architecture to formalise a space that needs to be a worthy representative of the city centre."

It clearly fails to do this, however. The elongated mosaic-clad half-dome is particularly eccentric; obviously intended to defer to the dome of City Hall, it only succeeds in competing with its august neighbour. The steel gantry extending from the parapet is another gratuitous eccentricity, with no obvious purpose.

The main façade is also jarring. The squat, bunker-like ground floor, with its cut-out entrance, resembles a security installation.

Above it, the outer glazed "skin" sits uneasily in front of an inner leaf of timber and glass; this probably accounts for the use of dayglo green strip lighting to distract passers-by at night.

The building is otherwise clad in polished stone, supposedly to reflect the more ornate façade of the former Munster and Leinster Bank (now AIB) on the east side of Palace Street. But the stone merely makes it appear more heavy-handed than it would have been if lighter materials - such as glass - had been used instead.

The west side of the building is curiously blank, except for a flying staircase (in galvanised steel) that leads down to the plaza from a doorway on the first floor. This is probably a fire escape, since it appears to serve no other purpose; it was originally intended to be a separate entrance to the four office floors.

Archaeological remains, including a defensive ditch of the old city wall, prohibited building the underground museum originally envisaged. A tiny chamber, echoing Micha Ullman's book-burning monument in Berlin's Bebelplatz, has a rooflight and a competition is to be held to fill it with something on the Bloomsday theme. Apart from some spindly trees in the background, the plaza has 12 granite-topped seats (with studs to deter skateboarders) that light up at night. However, it is planned that the café under City Hall will spill out onto the plaza, with tables and chairs under white umbrellas, so that should enliven the space during the day.

The Archeire website (archeire.com) is full of criticism. "It's such a huge disappointment," says Paul Clerkin, its moderator. "A fabulous site surrounded by some great buildings, it screamed for lightness of touch but instead we have Son of Sam." Another blogger wrote: "I liked this street much better with only one Sick and Indigent house on it".

Dublin City Council deserves credit for having the guts to go ahead with other speculative office blocks, such as architect Shay Cleary's building beside the Mansion House or Donnelly Turpin's office in Tara Street, now occupied by The Irish Times. But everyone is capable of making a wrong call, and the new Dame Street building is just that.

It may even be the most detested new addition to the city - and the fact that it stands on the main civic processional route between Christ Church and Parnell Square makes it almost unforgivable.