Smithfield has often been likened, at least in terms of its dimensions, to the Piazza Navona. In truth, it is actually somewhat longer and narrower than that great square in Rome and the comparison is more than a little far-fetched; it is another indication that we are losing the run of ourselves.

For it is already clear that Smithfield will never have the architectural unity of the Piazza Navona, which was laid out in the 17th century on the site of Domitian's Stadium, with Bernini's Baroque masterpiece, the Fountain of the Four Rivers, standing in the middle, overlooked by Boromini's Baroque church of Sant' Agnese.

The Piazza Navona is lined with palazzi and lesser buildings, all of them contributing to its overall sense of harmony. But the chances that Smithfield will replicate this in Dublin, albeit in a contemporary style, are being frittered away by cumulative planning decisions that appear to have little to do with coherent urban design.

The first major development in the area, Smithfield Village, was conceived by Terry Devey, of Heritage Properties, in the early 1990s. He had bought the former Jameson Distillery site and hired A+D Wejchert to design a mixed-use scheme, incorporating apartments and a hotel on the upper floors and retail/leisure uses at street level.

Though it seemed very ambitious at the time, its scale is modest compared to what is now being built or planned in Smithfield. Even so, the characteristic osthouse-style towers were reduced in height by Dublin Corporation's planners, to the dismay of Andrej Wejchert, who believes the effect was to turn them into "stumps".

Since then, the booming economy and stupendously high land prices - reflecting developer interest in this long-neglected area - have raised the stakes much higher. Veteran developer John Byrne, for example, is building a seven-storey office block at the southern end of Smithfield with a corner tower feature that rises to nine storeys.

This massive block designed by Brian O'Halloran and Associates, which the Office of Public Works has agreed to lease for the Land Registry, looms up over the former parish house of St Paul's Church on Arran Quay and its tower even competes for attention with the steeple of that venerable, but now vacant, Catholic church.

Directly across from Smithfield Village, Fusano Properties recently received a favourable decision from the planners for a massive scheme that will stand seven storeys high on the frontage of the square, with a setback penthouse level taking it above the height of the gas braziers on top of McGarry Ni Eanaigh's 12 lighting masts.

As previously reported, the centre-piece of this very dense development will be a 23-storey residential tower with panoramic views over the city from its upper floors. This slim tower, designed by Horan Keogan Ryan, will rise to a height of 77 metres - more than 20 metres higher than the observation deck above the old Jameson chimney.

The tower is to be clad in glass, stone and terracotta panelling similar to some of the new buildings on Potsdamer Platz in Berlin. According to Jerry Ryan, the architect in charge of the scheme, it is intended as a modern interpretation of the campanile so characteristic of Italian urban squares, notably the main piazza in Siena.

Some consideration was given by the planners to reducing the height of the tower from 23 to 16 storeys, but in the end they swallowed hard and decided to permit it. An Taisce will be appealing against the entire scheme, largely on height and density grounds, so the eventual outcome will be determined by An Bord Pleanala.

One "plus" in the proposed development is that it includes a three-level basement car-park, with almost 800 spaces. Some of these spaces would be available for short-term public use; originally, the corporation's plans included a car-park beneath Smithfield, but this was dropped on cost grounds.

FUSANO paid £8 million for the site, formerly occupied by Duffy's scrapyard, and so needs to get its pound of flesh. Indeed, it is a real indication of the extortionately high land values in the area that Bru na bhFiann, a three-storey building on Queen Street built within the last decade, is to be demolished as part of the scheme.

The old soldiers living there will be rehoused further up the street - assuming that a dispute over site boundaries between Fusano and Zoe Developments can be resolved. But the proposed demolition of a building less than 10 years old shows how disposable such tangible things have become in this rip-roaring era of development.

A Galway-based consortium has also got the go-ahead for another large scheme beside the Fusano site though, in this case, the gargantuan scale of its central feature - variously described as a "glass bullet" or "crystal ship" - has been reduced by about eight metres while the block facing North King Street will not exceed four storeys.

Also on North King Street, there is a question mark over the facades of a pair of quite ordinary three-storey listed buildings that collapsed earlier this year. One observer acidly commented that they would "look much better on the back of a lorry", which is where they ought to be consigned to make way for something more in scale.

Meanwhile, two storeys are being added to the undistinguished Linders building at the southern end of Smithfield and Sam Stephenson has drawn up plans for the site next door, involving an offices and retail scheme of equivalent height. A lower block had been contemplated here, but inevitably it grew based on precedent of its neighbours.

What all of this raises is what should happen to the corporation housing scheme at the northern end of Smithfield, where the brown brick houses are just three storeys high, falling to just two storeys along the adjoining side street. This scheme, like so many others in the inner city, was the limit of civic aspirations in the 1980s.

No doubt the residents are quite attached to their homes; some, indeed, have purchased them from the corporation in recent years and, on occasion, a "for sale" sign may be seen. But there can be no doubt that this scheme of some 60 houses, redolent of north Clondalkin, represents a waste of scarce urban land in what is now a valuable area.

IF AN appropriate urban scale is to be achieved in Smithfield, some consideration will have to be given to the possibility of replacing these houses with blocks of flats or a mix of flats and duplex units, with retail (or workshop/enterprise units) at street level, such as the much-praised corporation scheme at Jervis Street/Parnell Street.

What must be remembered in the case of Smithfield is that the whole area will be served by the Tallaght Luas line, running through the southern end of the square from Benburb Street to Chancery Street. And the Residential Density Guidelines are quite explicit in locating more dense housing in the vicinity of public transport routes.

The big question is what impact all of the developments planned for Smithfield will have on the re-designed public space, which has already won a major European prize for its architects. There is also an issue about how this space is to be used and managed over time, so that it becomes an essential element of the social fabric of the city.