Since the late twentieth century, the concept of green infrastructure (GI) has gained increasing recognition as a valuable approach to spatial planning. Although GI is an eminently spatial element, there are still few instances where this type of infrastructure has been given explicit definition and delimitation. It is therefore necessary to develop methods capable of defining these infrastructures through explicit spatial suitability analysis of their component dimensions. Here, we present a methodology based on the use of Geographic Information Systems (GIS) to identify and map potential areas for inclusion in a GI in the Henares Corridor (Madrid-Guadalajara, Spain). We analysed four factors (the contribution to ecosystem services, ecological connectivity, ecological status, and proximity/potential accessibility to the public), combined using multi-criteria evaluation techniques, thus offering different alternatives for defining and designing GI. The GI maps obtained show better results in less restrictive situations, which could be considered to articulate the existing protected areas. [ABSTRACT FROM AUTHOR]