A multiscale urban climate modeling approach is used to study the urban climate at both city and neighborhood scales. The mesoscale meteorological model WRF (Weather Research and Forecasting), enhanced with urban land use parameterization, simulates the urban microclimate in Geneva and Fribourg, Switzerland, during the summer of 2019. Heat exposure indices are mapped to quantify the urban heat island (UHI) effect and identify multiple hot spots, enabling the selection of a representative heatwave for detailed microscale analysis. Microscale simulations are conducted using urbanMicroclimateFoam, a open-access numerical model developed by the authors based on OpenFOAM. These simulations are driven by boundary conditions from the mesoscale WRF outputs. The microscale study focuses on the Schoenberg neighborhood in Fribourg, analyzing current conditions and three future scenarios: densification, increased vegetation, and a combined Eco-city scenario. Densification generally increases air temperature and worsens thermal comfort due to reduced wind flow and increased heat from sunlit building facades. However, some areas benefit from additional shading and cooler downdrafts from taller buildings. The Eco-city scenario demonstrates that adding vegetation can mitigate the negative impacts of densification. Shading from trees and evapotranspiration contribute to lower temperatures and improved comfort. Nonetheless, in areas where ventilation is hindered, thermal comfort can deteriorate compared to the present situation. These findings highlight the importance of strategic planning in urban design. Incorporating vegetation thoughtfully can offset some adverse effects of densification and support climate-resilient urban development.