Plans for a £215m extension to London's Tate Modern gallery have been given the go-ahead by Southwark Council.
"We are delighted," said Tate director Sir Nicholas Serota, who hopes to open the 11-floor glass building in time for the 2012 Olympics in London.
"This decision would not have been possible without the involvement and support of local residents," he added.
An electricity sub-station will have to be moved to make way for the building on London's South Bank.
The site is intended to provide more space for the Tate's collection and will help combat overcrowding at the gallery, which received 4.9m visitors last year.
The 23,000 square metres of space will include areas for contemporary art, several galleries and two performance zones.
"Facilities for young people will be central to the new development, and learning and visitor engagement will be at its heart," said a Tate spokeswoman.
Tate director Sir Nicholas Serota is "confident" it will open in 2012
The project was designed by Swiss architects Herzog and de Meuron.
Last month, they received the Royal Institute of British Architects' gold medal for work including their redevelopment of the Tate Modern.
The cost is expected to be comparable to Tate Modern's original construction bill.
The London Development Agency - overseen by the capital's mayor Ken Livingstone - is providing £7m towards the project.
What do you think of the plans for the Tate Modern? You sent us your comments.
This is an absolute abomination! I have no issue with modern design, but in the right setting. This is more suited to a silicone valley environment. Please, approve something that will enhance the area, not stick out like a sore thumb.
I like the design as it shows architecture can be a good thing when considered properly but I have one gripe, why could they not simply buy Battersea Power Station and use that instead? It is a far grander building, has more space surrounding it for parking space and outside exhibitions and would, at last, provide some meaning to a much-loved icon.
I am not sure if I suffer from Prince Charles Syndrome but that really is the most repulsive and out of character extension I have ever seen. Another London landmark to be ruined.
Michael Dupree, London, UK
At least when you see this horrific 'work of modern art', you will know what you're going to see when you get in there!
Jordan Taylor, London
Like any piece of art, it is impossible to appreciate the impact and effect without experiencing it up close. A tiny picture on a computer or TV screen or in a newspaper or magazine is going to give you a very limited impression of what it will be really like. You can't look at a picture of a glass of wine to decide whether it is good wine or not.
Dominic, Enfield, UK
The extension is an engaging, modern and eye-catching design that works exceptionally well in tandem with the simple lines of Bankside Power Station. As one of the worlds most popular art galleries, the Tate Modern deserves only the best possible extension of its space to allow it to maintain is rightful place on the world stage. However I have no doubt whatsoever that the NIMBYies who opposed the original conversion of a decaying eyesore will just kneel over and allow this expansion to be built. I implore all those who care one iota about architecture and indeed art to stand firm in the state of such criticism and voice their support for this wonderful and necessary build.
Jack Tindale, Barnsley, South Yorkshire
I visit the Tate Modern about 3 - 4 times a year. I find it a particularly vibrant, people friendly and accessible gallery. The variety of the permanent collection (including the impressive Rothko Room) and quality of exhibitions is superb.
Susan Miller, Cambridge UK
It looks fantastic. Why can't we have more creative architecture? Everyone raved about Tate Modern when it opened - it is, quite frankly, the dullest modern art museum I have ever been in. Dull as dishwater, conservative Victoriana. With this, and the Shard, we may actually become known for more than our historical buildings.
It is as ugly as the art on display in the Tate Modern.
Nigel Crane, Romford, England
Tate Modern is a great institution and needs more space, but why does it have to be in glass. The 1930s brick of the old power station has lasted well. Will the proposed extension be in such a good state in even 20 years? I think not.
Jeremy Hodge, Aylesbury, UK
All power to the Tate's elbow! Their's has been a spectacular success story in terms of visitor count, and the new extension is well in keeping with the image of the Tate Modern. And hats off to Southwark Council and local residents for showing such farsightedness.
The design breaks imaginary and architectural boundaries and expresses a need for a more modern London, visually and contextually. The Tate Modern design will be our Sydney Opera House, our NY Guggenheim. And not another Millennium Dome.
Paul C Davies, New Malden, Surrey
Oh dear. Yet another abomination to pollute the London skyline. It is a shame that councils seem hell-bent on destroying any architectural coherence that the city might once have had. Who really enjoys these things anyway? Let us hope that the predictably poor planning and rocketing costs put pay to this disaster before it is completed. DWR.
DW Roberts, London, UK
From these pictures, it looks like the extension will overwhelm and vastly detract from the strikingly beautiful older building.
Peter, Aldershot, Hampshire
I've entered the Tate Modern several times and rarely progressed further than the Turbine Hall, which seems to me to be an enormous waste of space which could accommodate the contents of the proposed extension several times over. If anything other than public money was being spent here methinks that something a little more attractive and practical would be built.
I think it is a fantastic addition, and celebrates the Tate's legacy of being forward thinking. I would also like to see the Tate Modern have a dedicated space for up and coming artists who could apply direct to the Tate with their portfolio.
James Appleby, Leeds