Tate Modern and architects Herzog & de Meuron have revealed their revised plans for the £215m development of the museum.

The original design – which resembled a stack of bricks – has been scrapped, making way for a new three-dimensional trapezoid-shaped structure. The 11-storey building will be 65m (213ft) tall and will add 21,500sq m (230,400sq ft) to the Tate Modern's existing 35,000sq m (377,000sq ft).

Three oil tanks from the former power station will be retained and used as exhibition space and as the foundation for the new building.

The new-look Tate Modern will also boast two new publics spaces – a southern square modelled as a city piazza and new child-friendly gardens to the west.

A planning application is expected to be submitted within the coming weeks, and work is planned to begin next year. The new building is expected to be completed in time for the London 2012 Olympics.

The project, which is estimated to cost £215m at 2012 prices, has already received £50m from the government, £7m from the London Development Agency and £13m from the private sector. Details: www.tate.org.uk