Recent urban design studies have shown that differences in urban patterns have a strong influence on the microclimate and thermal comfort at street level. This book intends to investigate the impact of traditional and modern urban forms on outdoor thermal comfort in Aleppo, Syria. It defines the urban microclimate and introduces the influencing factors, it also explores the aspects that affect the thermal comfort conditions and reviews related researches. The method of investigation adopts two approaches, field measurements and microclimate simulation. The assessment of outdoor thermal comfort was conducted based on the calculation of the Physiologically Equivalent Temperature (PET) and Predicted Mean Vote (PMV) taking into account field measurements and available records. Furthermore, micro-scale numerical models were used to simulate microclimate at specific locations. This book sheds light on how groups of buildings can modify the climatic and thermal comfort conditions surrounding it, and it should be useful to professionals in urban design and town planning fields, and anyone with background in architecture, environmental design, urban simulation or urban physics.