There may be doubts about whether Tate Modern's £215 million extension will be ready for 2012, but you can get a sneak peek at the new building today by heading to Mandela Way in Bermondsey.
The structure, which is almost 4.5 metres tall, is made of concrete and brick and gives an indication of the lattice pattern of bricks planned for the extension to the former Bankside Power Station building.
Tate received planning permission for the temporary structure last year, which will be used to test the building's unusual materials. It is expected to remain in situ for up to two years.
The bricks are arranged in a perforated screen through which light can filter during the day and through which the building will glow at night.
Tate director Sir Nicholas Serota told a press conference last month that fundraising for the extension to the gallery at Bankside is "now roughly speaking half way towards our target of just over £200 million".
The Tate Store site at Mandela Way has been earmarked by Tate for the development of a new National Art Collections Centre to be run jointly with the National Portrait Gallery. These plans failed to attract the backing of the Heritage Lottery Fund.
Next week Southwark's planning committee will consider an application by Tate for the renewal of the planning permission for the Grimshaw-designed art collections centre. Permission lapsed on 13 August and Tate is seeking a further five years to raise funds and build the collection centre.