Information architecture concerns how to structure the content of an information space. Information architects design information spaces. Staying with the notion of information space leads us to the realisation that people need to be able to both conceptualise an information space and find their way through that information space to where they want to go. People need to be able to navigate information space. In this chapter we explore two key issues of web site design; information architecture and the design of navigation support. In order to do this we draw upon theories of information spaces and theories of navigation in urban spaces. From these theories a number of practical features of web sites are described.