Trustees at Tate Modern in London have unveiled plans for a £165m redevelopment of the museum.

The extension, a 230ft (70m) tall, 23,000sq ft (2,136sq m) pyramid structure designed by Herzog & de Meuron architects, will increase the size of Tate Modern by 60 per cent.

As well as providing more space for contemporary art – including photography, film, video and performance – the development will also include cafés, restaurants, shops and a patron’s lounge. More than 1,000 new trees will also be planted.

London mayor Ken Livingstone announced that the London Development Agency would be contributing £7m towards the scheme, with the hope that the project would be ready by the 2012 Olympics. The rest of the money would come from private and public sector sources.

An application for planning approval will be submitted by autumn this year and a decision is expected by Spring 2007. Details: www.tate.org.uk

Photograph: Night view of the new development of Tate Modern from the South. Copyright: Hayes Davidson