The role of urban parks has gained interest in urban health research. However, there are currently no clear definitions of these urban assets as exposure variable across the literature, which do have implications for the analysis. In this study, we exhibit an approach to design a comprehensive spatial database of urban parks in cities, using the example of Madrid. This approach consisted of the combination of different spatial databases containing information about parks and green spaces in the city of Madrid, and then a spatial processing to keep only those that met the selected criteria for urban park definition: accessible for pedestrians (to have at least one path around or through the area) and with the minimum size suitable (bigger than 0.50 ha) for physical activity. This approach can be helpful to design spatial databases that enable conducting epidemiological studies on the relationship between urban parks and population health.