Imagine New York without the twin towers of the World Centre or Chicago without the Sears Tower. What would Hong Kong be without its myriad skyscrapers set against the Peak? Are tall buildings necessary to ensure a city's role as a leading centre for commerce and finance?For years, this question has been vexing planners in London, a notoriously low-rise city. This week, the London Planning Advisory Committee (LPAC) will issue a report concluding that there is no evidence to suggest that tall buildings are to be built, the report, says they should be limited to certain areas such as the fringes of London's historic Square Mile and Docklands.The report, although strictly an advisory document, is likely to be a blow to several financial institutions who would like to occupy large central City properties and to the developers who want to build them."Lots of tenants, particularly Americans, like tall buildings," says Peter Thornton, chief executive of Greycoat, a specialist in City office developments. "Whenever we have had a tower in our portfolio, we have found it rented out much faster than other buildings." The tenants, he says, not only like the light and views, but found easier to divide and manage.LPAC's report stems from the filing of a now abandoned application two years ago to build a 90-storey Millennium tower on the site of the bombed-out Baltic Exchange. Now, Swiss Re, the re-insurance group, has conditionally agreed to buy the site, provided it will be allowed to build a structure large enough to suit its needs.The evolution of skyscrapers in other cities, industry experts say, is partly a function of geology. In New York, the city's bedrock of mica schist and granite made it particularly suitable for grounding tall buildings, says Michael Dow, chairman and chief executive at the US division of consultants Jones Lang Wootton.Moreover, Manhattan is an island and despite valiant efforts to expand through landfill, space remains limited. "The merit of tall is that it maximises the value of very expensive land," he notes. A recently constructed headquarters building for International Business in Westchester, north of New York City, where land is relatively cheap, is low and wide, he notes.Developers say that there are some pragmatic reasons why tenants appear to like high-rise buildings.First, those seeking large space find it more efficient to travel by elevator within a skyscraper than to traverse the length of a groundscraper on foot. Also, Multi-let skyscraper can be more easily adjusted to make room for growing tenants by simply freeing up a few floors above or below existing premises."They like the views, they like the big floorplates and they like the corner offices," Mr Dow says. Indeed, the predilection for corner offices, among senior executives has led to interesting building design. The signature tower building at Canada Square at Canary Wharf in London's docklands is cleverly designed to incorporate three corners in each of its four corners, trebling the number of corner offices on each of its 50 storeys.But there is another, more suitable, aspect to tall buildings. H. Gordon Wyllie, executive director and chief executive of the International Association of Corporate Real Estate Executives (Nacore), a Miami-based organisation of corporate tenants, says the issue one of corporate prestige.Mr Wyllie, who had headed the real estate services for what was then South East Bancorp, was responsible for building the bank's corporate headquarters Gerald Hines. "It was a statement. We wanted the tallest headquarters in town," he says.

The Sears tower in Chicago is a similar structure. "Tenants will pay the highest rents for the predominant address in town," Mr Wyllie says.Skyscrapers may be, not to put too fine a point on it, a kind of corporate virility symbol. But Mr Wyllie argues that the question of whether or not tall buildings ought to be built cannot be seen in isolation from other considerations. The bigger question, he says, is what sort of city do planners wish to create. Do they wish to encourage inner city living? Do they wish to create a downtown centre? If so, what sort of retailing facilities should be encouraged? What are the mass transit needs? The question is not whether or not so build tall buildings but the sort of environment planners hope to create. "You can't do this in a vacuum," he says.Even cities such as Paris, which has eschewed tall buildings, have recognised the demand for high rise modern office space, although most is limited to the La Defense area on the Paris fringe.Washington DC, patterned on Paris and with similar height restrictions, has never emerged as a strong financial centre, perhaps unusually for a nation's capital city. Would Washington's commercial life have been different in a more relaxed planning regime? Big buildings do change the chemistry of cities. "It's these canyons of buildings which give a city its character," Mr Dow says. "It is a high density of population which gives a city a buzz."