Our extension to the Science Museum is devoted to contemporary science and technology. The creation of this new wing presented a practical challenge to make a museum environment that was inherently flexible and adaptable but at the same time operationally efficient and easy to maintain. The brief for the public areas of the building required flexible, column-free, exhibition space and the inclusion of a 450 seat IMAX 3-D cinema and catering facilities. Our strategy was to maximise the buildable area on the site by making a compact envelope of about 11,000m2 that left sufficient site area for further development of similar size in the future. As part of this approach the cinema is suspended in the space, leaving the entire ground floor free for temporary exhibits. Because science can be both marvellous and surprising we sought to create a design which amazes and engenders a mood of heightened expectation, and an experience of theatre in which the drama is the building and its contents. The building’s deep blue interior contrasts strongly with the Victorian buildings that make up the rest of the Science Museum and evokes a sense of mystery, hinting at the infinite possibilities of science. Along the frontage facing Queen’s Gate, extremely sensitive in planning terms, we have designed a separate conference building (the Wellcome Wolfson Building). This screens the space reserved for the Museum’s future expansion.