This chapter discusses the role that design and space play in the UK Parliament. The architecture and design of parliamentary buildings and chambers occupy a central place in political culture. In the case of the Palace of Westminster, three elements must be highlighted: the external projection of the building, the internal structure and the manner in which it defines and dictates the use of space, and the manner in which the internal structures affect user-interactions in more subtle ways (for example, inspiring deference, augmenting partisanship, or perpetuating and preventing forms of democratic inequality). After explaining ‘how’ and ‘why’ design and space matter, the chapter traces the history of design and space in the Palace of Westminster as well as its building and rebuilding. It also considers attempts to change the design and architecture of Parliament and the difficulties of assessing design and space.