The existing Herbarium buildings at Kew have housed a botanic library and dried plant specimens, collected from all over the world, since 1853. Edward Cullinan Architects have designed a new 5,000sq m extension to provide a modern archive for existing and future acquisitions.Kew is a World Heritage Site and the design had to integrate with and enhance the setting for the existing listed building and protected trees near the banks of the Thames. A circular set of rooms both connect the old herbarium to the new wing and act as a compositional device, pivoting the orientation of the new archive vaults to align with the old boundary wall.A palette of materials was selected to complement the old buildings in a harmonious way, but also to meet the functional requirements of the highly controlled environment for storing the collections.To enter the vaults, botanists walk along an undulating corridor where the deep curves allow for tables to lay specimens out for viewing in daylight.