Starting from Zero

"A failure to rise to an occasion of historical magnitude...mediocrity, constructed at vast public expense. Ignorance is the brick from which this wretched edifice is built ... many New Yorkers are disappointed beyond belief." Thus spake Herbert Muschamp, the renowned architecture critic of the New York Times, of the official proposals to rebuild on the site of Ground Zero.

As soon as the towers fell it was clear that something would need to be built in their place - and that a memorial would have to be built equal to the scale of the 11 September catastrophe. How this should be achieved has been the subject of fierce debate.

In June the official master plans for the site were unveiled by the practice of Beyer, Blinder, Belle, known to unkind critics as Blah, Blah and Blah. They were commissioned by the Port Authority of New York and New Jersey and the Lower Manhattan Development Corporation, the two public bodies responsible for the 16-acre site. In a show of openness and consultation, the public was asked what it thought of six variations on the scheme, but there was no real choice - the designs just showed office blocks and open spaces distributed in six different ways, much as a parent tries to entice its child by cutting processed cheese into interesting shapes. In all six, the bland substance of the development remained exactly the same.

The public, by and large, didn't think much of it, and now the Port Authority and the LMDC are scuttling around in an effort to retrieve the situation. While Beyer, Blinder, Belle are still officially on board, an invitation has gone to architects around the world to inject some creativity into the proceedings.

Meanwhile, the biter has been bit. Last week alternative proposals, commissioned by Muschamp and his newspaper, went on show at the Venice Architecture Biennale, the world's biggest get-together of architects. A debate was held where Muschamp himself came under fire. The proposals he commissioned failed to address all the complexities of the site, it was argued. Since it is a place of global significance, it was added, why was its future being treated as a parochial New York affair?

Yet more ideas for Ground Zero, ranging from the sublime to the ridiculous, are also on show in Venice, in the United States' national pavilion. These were originally commissioned by a private gallery, Max Protetch, when the embers were still warm, and they had leading American commentators spitting with rage. They did not think that a nation's response to a national tragedy should be left in the hands of a private gallery.

So, where there should be noble aspirations and common purpose, there is rancour, confusion, opportunism and dissent. This is not unusual - witness the rows in Britain about the smaller matter of Princess Diana's memorial - but it is also desperately sad. There is every danger that the eventual outcome will be a compromise, in which the processed cheese will be unpalatably garnished with symbols of grief and art.

When London burnt down in the Great Fire, Sir Christopher Wren's reconstruction of its monuments made the city greater than it was before.

Since then the precedents for Ground Zero have not been entirely encouraging. After London burned again in the Blitz there was much talk of visionary reconstruction, which translated only into compromised reality. When Berlin filled the gaps left by war and the Wall, the result was largely corporate blandness.

At Ground Zero everything is still possible, but it is complicated by several factors. It is a shrine, around which shops and stalls have already gathered selling the sort of souvenirs, emotionally charged, if of dubious taste, that you get outside shrines in Catholic countries: miniature sculptures, decorated clocks and table ornaments in which firemen and the twin towers take the place of the Madonna and the Cross.

But it is also a major piece of real estate, with the potential for a prodigious quantity of valuable office space. While some relatives of Ground Zero's victims would like the site left permanently empty, the Port Authority is legally obliged to maximise its profits, on behalf of New York's taxpayers. Ownership is complex. A developer called Larry Silverstein bought a lease on the towers shortly before they were destroyed. Having planned on doing no more than refurbishing them and upping the rents, he suddenly found himself with an immense construction project on his hands.

Next, whatever is built here has to match the iconic power of the twin towers themselves which, when they still stood, looked like monuments to an unknown event. Without-them the New York skyline now looks curiously old-fashioned. And all this has to be done without making the new development into a too obvious target, an invitation to future terrorists simply to repeat the events of 11 September.

Yet it is still possible to create something on Ground Zero equal to both its emotional load and Manhattan's majestic architecture. Here, with due deference to the greater knowledge of those closer to the scene, are some suggestions for guiding principles.

First, there is nothing wrong with larger-scale commercial development-Among al Qaeda's targets was the business life of New York, so the rebirth of that life would be a fitting riposte.

Second, there should be nothing ordinary or conventional about the new commercial development. The new buildings should carry the consciousness and memory of 11 September, so they act as living memorials. This is infinitely preferable to the formula implicit in the Beyer, Blinder, Belle schemes, where a purpose-designed memorial or garden frees the commercial structures of any duty to commemorate.

Third, and this is a tall order in Bush's nation, the new buildings should show some awareness of the reasons why the United States attract hostility. The World Trade Centre towers were magnificent but aggressive and excluding, and it is the same combination of qualities that inspire resentment - often unfair but still real - of America. New buildings on Ground Zero should be strong, but also delicate and sensitive.

Lastly, the new buildings should not be skyscrapers. The twin towers were so memorable that any new tower is almost certain to suffer by comparison. New construction on the site can be large and imposing, but there are other ways to achieve this than by sheer height. It is better to leave the airspace inhabited by the twin towers' ghost.