The historical built environment (HBE) is constantly prone to many risks causing sudden (e.g., earthquakes and terrorist attacks) or slow (e.g., climate change-related and environmental pollution) onset of emergency conditions. Morphological, physical, and constructive characteristics are critically linked to system vulnerability and users’ exposure. In particular, open spaces (OSs) in the HBE represent typical attractors for the community in urban areas for leisure and touristic purposes and critical scenarios in case of a disaster. In fact, besides daily and hourly temporalities in everyday use, OSs also play a pivotal role in the immediate disaster response phases, considering sudden-onset events. Understanding which scenarios characterize OSs is critical to evaluate them from a multi-risk perspective and to propose effective mitigation strategies in multiple critical situations. To this end, this work offers a survey form template of the OS within the HBE according to a holistic but quick-to-apply approach. Placed in the context of the Project of Relevant National Interest (PRIN) BE S2ECURe, the survey form assesses the relationships between frontier elements and those contained in the OSs, focusing on literature-based identification of vulnerability, exposure, and hazard factors affecting risk. These factors are organized into five sections as the basis for classification criteria of OSs: (1) morpho-typological, (2) geometrical-spatial, (3) constructive, (4) use, and (5) context. The application to eight case studies contributes to the validation of the survey, showing its ability to trace both the level of complexity and the main characteristics of the analyzed scenario. Furthermore, the survey form can be properly and quickly applied by non-specialized technicians, such as local authorities, thus representing the first step to support planners in data collection and risk assessment of historical OSs.