The Russian invasion of Ukraine serves as another illustration of the urban nature of contemporary war. While cities have been battlegrounds throughout history, it is only in the last few decades that military thinkers and strategists have seriously started to consider urban warfare as imperative – that cities have become unavoidable in war. In this article, I provide an overview of the type of urban warfare we have seen unfolding in Ukraine so far, and discuss what appear to be mismatches between these urban battles and the type of urban wars anticipated and planned for by Western military organizations and strategic thinkers. In some respects, the general character of the urban warfare we see unfolding in Ukraine has more in common with medieval than modern warfare. While Russia pursues a brutal combination of siege warfare with heavy and indiscriminate bombardment of cities, Ukraine has developed an effective urbanized defence, not only by using the urban terrain to its advantage, but by using cities as fortresses and bases of operation.