The sound environment in urban areas is complex, as caused by many sources of sound and influenced by a variety of acoustic propagation effects. In order to combat noise and create acoustic environments of high quality, it is of utmost importance to be able to predict the time dependent sound field in such areas. Engineering methods are useful for a fast analysis and noise mapping purposes, but remain tools with limitations. Besides, computational modelling of urban acoustics, i.e. the group of wave-based solution methods, has obtained its role for complex environments as well as for research purposes. These computational models have become more mature in the recent decade. This paper addresses questions that are of interest for all scientists and research-oriented engineers in this field, as well as researchers in related fields of urban physics. The questions relate to the need for computational methods, the relevance of including various urban propagation effects in computational modelling, and to the preferable computational methods and approaches to use. Answers are based on scientific work by the author and many other urban acoustic researchers, and will also contain visionary opinions of the author.