Will Sir Norman Foster's building be the tallest in Europe, or just pie in the sky?

A 1,265ft kidney-shaped glass building which would be the tallest in Europe was unveiled yesterday as the architect Sir Norman Foster's vision for the bombed Baltic Exchange site in the City of London.

Plans for the pounds 400m skyscraper set the year 2000 for a "topping out" ceremony marking London's pre-eminence as a financial centre for the millennium. The structure will include restaurants and bars on a 1,000ft-high public viewing platform, 40 apartments, offices and trading floors.

Although the building would dwarf neighbouring towers, Sir Norman denied that it would overpower the skyline.

He said: "Tall buildings are expressions of the energy and aspirations of world-class modern cities. The London Millennium Tower will be a statement of confidence in the City for the next century ... a sign that London does command a central world-league position."

Although there were exciting projects for the millennium planned in the City, there was no new building and this was a "very good opportunity". It would not be a "remote and isolated building sticking out like a stick of rhubarb," he added.

The unveiling of the proposals came after months of speculation over the future of the site which was severely damaged by an IRA bomb in 1992.

But the futuristic design is bound to cause controversy and raise suspicions that it will never be built. The building will require planning consent from English Heritage as it involves pulling down the Grade II listed remains of the old Baltic Exchange. In the wake of the bombing, English Heritage had insisted the exchange, which had a neoclassical facade and a striking teak-panelled trading floor, should be restored.

But when work was carried out last year in preparation for a separate, successful planning application incorporating the exchange into a new building, the severity of the damage became clear and the Corporation of London asked English Heritage if a new design might be considered.

An English Heritage spokeswoman said yesterday: "We're extremely sceptical about a building of this size on that site. We think it would dominate the City skyline and have a major impact on surrounding streets."

They could make no detailed comment until an application was submitted, but would want a full environmental survey, she said. At a press conference yesterday, Sir Norman stressed that extensive tests were being carried out to prevent a wind-tunnel effect around the tower and to protect the "micro-climate" at its base.

The form of the structure would be "free-flowing and sculptural" with the effect of sunlight hitting the curved glass facade making it appear "elegantly slender" and providing a different view from each side.

Security would be maintained by providing public access only from glass lifts outside the building, leaving internal lifts for the 8,000 people expected to work and live inside.

The building will be the third tallest building in the world and Sir Norman was delighted. "The thrill is doing it here in London and not having to travel to the other side of the world," he said.

Alan Winter, managing director of the developers Trafalgar House Property, said they hoped to submit the planning application next month and begin next work next year for completion by 2001. But any public inquiry would delay the timescale.

The company needed an "anchor tenant" committed to the project before it could go ahead, and was in talks with several interested companies.