The winning design for a new £650m US Embassy to be built in west London has been revealed.
Pennsylvania firm KieranTimberlake beat 36 companies in the contest to build the embassy in Nine Elms, Wandsworth.
But critics have described the winning design as being "like a fortress" and derided similarities between it and the old embassy in Mayfair.
Wandsworth Council must approve the new design. The US hopes to start building in 2013 and complete work by 2017.
A US Embassy spokesman said: "KieranTimberlake's design met the goal of creating a modern, welcoming, timeless, safe and energy-efficient embassy for the 21st Century.
Unless they are restricted to designing a building to look like a fortress it is not what I would expect for what is supposed to be the greatest embassy building in the world
Mayfair residents' association
"Their concept holds the greatest potential for developing a truly iconic embassy and is on the leading edge of sustainable design."
But Antony Lorenz, chairman of the Mayfair residents' association - which has criticised onerous security measures at the old embassy - said: "It seems amazing the architects have followed a plan of the existing embassy.
"It looks almost identical with its concrete looking structure."
He added: "Unless they are restricted to designing a building to look like a fortress it is not what I would expect for what is supposed to be the greatest embassy building in the world.
"I am absolutely shocked."
Wandsworth Council granted outline permission for the embassy in September 2009, hoping it would "kick-start wider regeneration of the area".
Some 1,000 people will be able to work in the 12-storey, 45,000 square metre building.
It is being designed with the risk of terrorist attacks as a strong consideration.
It is set among landscaping including a pond, which acts as a natural security measure, the design team said.
James Timberlake, of Kieran Timberlake, said: "It meets and exceeds all the security requirements.
"We are using elements of landscaping that have been around for centuries. But it's not a fortress - we are able to use the landscape as a security device."
The embassy will be in the centre of the site and set back 30 metres from its boundaries to create a blast-proof zone.
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