Many powerful eyes will be focused on a significant building consultation that starts this week at the Corporation of London. KPF's Bishopsgate Tower - of which the AJ published the first images after a planning application was made on 22 June (AJ 23.06.05) - is to face widespread scrutiny.
A plethora of issues colour any consultation - and this process becomes more critical when the building in question is several hundred metres tall.
The new proposals would dwarf the 183m-high Tower 42, currently the City's tallest building. It would also eclipse the nearby Swiss Re building (180m), and would be only two metres shorter than Renzo Piano's proposed London Bridge Tower, or 'Shard of Glass', which has already been granted planning permission.
Sight lines, whether the structure fits into a cluster and how it meshes with pedestrian environments are all important considerations. They all have to be acceptable if the statutory consultees are to be brought onside. Given the changing shape of the variegated blanket that now swathes London, what are some of the current crucial visual impact issues which need to be debated when seeing such a mammoth building project safely home?
Peter Stewart, design consultant and former director of design review with CABE, splits these questions into 'top and bottom' issues. Bottom issues comprise ground-level design; the question of pedestrian environments around the building's base. Tall and thin buildings don't have as much room for the provision of services or make such an agreeable pedestrian experience - but land is at a premium.
All eyes will also be on the top of the building - the head and shoulders of a landmark, poking its nose above the masses and which can be seen for miles around. The KPF landmark in question, also known as 'DIFA tower', will be 307m high and comprise 88,000m 2 of offices, shops and public space if it goes up.
So no one is going to miss it.
'A building with a similar amount of space but that is 12 storeys is not going to make the same impact. The interesting thing is what views it will affect, and that needs to be illustrated thoroughly, ' says Stewart.
Photorealistic visualisations will help determine whether the new structure will detract attention from London's surrounding historical buildings, especially from a distance.
Stewart continues: 'The main sites which [such a building would] affect will be those of St Paul's and the Palace of Westminster. These views are considered not just in terms of potential obstruction but also in terms of the effect these new skyscrapers might have on the visual impact of historical buildings.' He highlights the view from Waterloo Bridge along the river as one of particular significance.
Richard Coleman, tall building consultant and self-professed pro-development conservationist, is more concerned about the new tower's relationship with William Tite's Royal Exchange - once the lynchpin of bustling City commerce, the clunking rattle of merchants' money now translated into the screams of the Stock Exchange when the FTSE crashes.
Coleman says: 'It seems that the new building is on the axis in line with the Royal Exchange's portico and eastern end - [where rounded corners sandwich two attached and two detached giant columns] - a line which corresponds to the location on which the new building would be constructed.' Presumably by total chance, one of the most historically important buildings in the City is in line with what could become the tallest.
Coleman refers to an ongoing cluster of buildings being approved by the Corporation of London in EC3 - a host of tower permissions still to be built such as KPF's 183m-tall Heron Tower (on another part of Bishopsgate) Nicholas Grimshaw's 217m-tall Minerva Tower, and Richard Rogers' 225m-tall Leadenhall Building. This cluster would be topped off by an apex formed by the 307m-tall KPF tower at its centre. The construction of the Bishopsgate tower would bring form to this cluster of buildings, says Coleman.
The consultant is keen to hark back to the work of the capital's skyscraper pioneer, Richard Seifert, the father of Tower 42. He sums up KPF's inheritance of Seifert's 'crown' - in terms of the design of tall towers - with optimism:
'I'm rather pleased about [these new designs]. The new building looks like it has the level of generosity of spirit that such a central building should have.
It will give form to something that would appear disparate without it.'
It seems that KPF is winning plaudits, although it needs to please political heavyweights in the mayor of London's office, as well as the likes of English Heritage.
The fact that this sculpted glazed tower nestles neatly in its context in London's eastern cluster, and will stay out of key views such as that of St Paul's dome from Ludgate Hill, has caused it to fare well so far.
Coleman already has the certainty of this permission clear in his mind. 'The only building it could potentially impact on is the Royal Exchange, but it's probably going to go through the planning system quite easily, ' he predicts. KPF better hope that, like Coleman, the rest of the consultees are seeing this mammoth tower with such a positive agenda.