Stirling Prize-winner Herzog & de Meuron has designed this 25,000m 2extension to the Walker Art Gallery in Minneapolis. The $67.5 million (£37.2 million) project will double the space available for the multidisciplinary centre, allowing for a substantial increase in the events programmed. It will provide new gallery space, a 385-seat performance space, a film theatre, a series of street-level and roof-top terraces, a library and an education facility. The extension programme will also double the size of the centre's sculpture garden. Walker director Kathy Halbreich described Herzog & de Meuron's designs as 'seamlessly weaving together indoor and outdoor spaces, the presentation and education facilities, and the institution as a whole with its surrounding city'.