Every year I excitedly await the opening of the Summer Pavilion, a programme involving a sequence of world-class architects transforming the space outside the Serpentine Gallery, Kensington Gardens into a temporary Pavilion. This year’s efforts are by Herzog & de Meuron and Ai Weiwei. It is the first time the Pavilion has been partly underground and it is a cool, contemplative space dotted with slightly mushroom-shaped cork stools. The design really invites you to plant yourself, linger, and look out and around – as opposed to just admiring the exterior. Our daughter, like all the children there, felt an irresistible urge to turn over the cork stools, line them up and otherwise personalise the space. The architects are interviewed here.