What term describes the steps taken to enhance the security of a building's exterior?

The term that best describes the steps taken to enhance the security of a building's exterior is "hardening." This concept refers specifically to the process of making a structure more resistant to various threats, such as unauthorized access, vandalism, or natural disasters. Hardening often involves implementing physical measures, such as installing security cameras, barriers, stronger locks, better lighting, and other protective features that deter potential intruders.

While other terms may describe aspects of security, they do not fully encapsulate the idea of enhancing a building's exterior security in the same focused manner. For example, "fortification" may imply significant structural changes or military-style defenses, which are not typically applicable to standard building security. "Securing" is a broader term that can encompass various types of security measures but lacks the specific connotation of increasing resilience. "Reinforcement" often implies the strengthening of existing structures but does not necessarily address all aspects of external security as comprehensively as hardening does. Hence, hardening is the most appropriate choice for describing the methods used to bolster a building's exterior security.