A £10m public inquiry into plans for the tallest building in Europe, known as the Shard of Glass is beginning on Tuesday.
The tower will cost £350m
Proposals for the 66-storey London Bridge Tower in the heart of London has attracted widespread opposition and fears that it would destroy London's skyline.
The tower, which would be 1,000 feet high, would be built on London Bridge station and cost £350m.
Simon Thurley, chief executive of English Heritage, said: "This is the wrong location for the tallest building in Europe.
"This colossal building is crammed onto a tiny site and looms oppressively over the surrounding area."
The project would involve demolishing the existing Southwark Towers and building apartments and offices, a hotel, shops, restaurants, a health spa and fitness club on the site.
It would become Europe's tallest mixed-use building.
The inquiry involves developers Sellar Property Group and the main opposition groups English Heritage and the Royal Historic Palaces.
Evidence will be given by the plan's supporters, the Mayor of London's
planning officers and Southwark Council.
London Mayor Ken Livingstone has said that he believes the Tower will "deliver a building and architecture of world class quality" and will not harm any listed buildings or conservation areas.
A spokeswoman for Southwark Council said: "We believe the tower will be of huge importance in bringing the wealth of the city southwards."
The inquiry includes four and five foot models of the proposed tower which have cost hundreds of thousands of pounds each.
Extra white glass
A spokesman for the developers said: "It will be an iconic landmark for London in the 21st Century."
The tower, designed by Renzo Piano, considered one of the top architects in
the world, will appear as a slender spire of glass with steeply sloping faces made of large shards of "extra white glass".
This combination will make the tower seem partly to disappear into the sky and it is likely to change its character and appearance with seasonal variations of light and weather.
The inquiry, at the Inquiry Room at Bankside House, south-east London, is expected to last four weeks.