  Computer models and information systems have been used for urban planning and
design since the 1950s. Their capacity for analysis and problem-solving has
increased substantially since then with hardware and software being able to
manage large amounts of data. The beginning of the 2000s brought better
technologies for data visualisation and intuitive software products and
nowadays they are being used to design and manipulate highly complex urban
systems. However, ontological and epistemological questions remain about the
nature of urban environments. What do we know about cities - and what is a city
exactly? What theoretical models can be applied to the study of cities? How do
we translate a city into data? What type of information really matters and what
do we want to communicate with them? What are the implications of computer
modelling for urban planning and design? This paper reviews how digital
technologies have been used to shape our understanding of cities and how they
impact the design and planning of cities. The point of depart is a scrutiny of
the emergence of modern planning in the nineteenth century when cities became a
scientific subject. A range of theories and concepts of the urban form and
urban growth developed during the twentieth century will be presented and then
linked to the first investigations involving the use of the computer for
modelling and planning. The paper concludes with some discussions around the
interaction of computing and urban theories.
