Urban morphology, that is the characteristic size, shape, orientation and distribution of buildings, plays a significant role in affecting the climate within cities. However, despite computational advances over the past decades, simulation studies investigating the effect of built form on the microclimate generally adopt either the array of cubes or the urban canyon model. What these models leave out are the microclimatic conditions within urban blocks and other complex environments that also constitute spaces of human activity. While the recently developed local climate zone (LCZ) classification system also took urban morphology to delineate ten urban categories, it also conceptualized built form as a cluster of free-standing buildings and therefore failed to account for semi-enclosed spaces. The aim of this study is to assess the effect of built form on the microclimate at the scale of the urban block. Taking the built environment of Budapest as a starting point, the study compares the microclimatic performance of four historic metropolitan urban block typologies. The comparative numerical study focuses on the influence of built form and orientation, and employes both a three- dimensional microclimate model (ENVI-met) and a high-level language for numerical computation and visualization (MATLAB). The presentation will compare the diurnal-cycles of air temperature, mean radiant temperature and Predicted Mean Vote of the four urban block configurations. The insights of this study could facilitate the development of targeted climate change adaptation strategies.