Persons with disabilities (PWD) account for 10–15% of the world’s population. The lack of accessibility in the built environment imposes a constraint on its use by these individuals. In heritage buildings, this restriction includes access to other main qualities in addition to use. This problematic issue has been dealt with in different sectors, especially in the tourism sector. The objective of this study is to design and implement a physical accessibility assessment tool adapted to the particularities of heritage buildings. The methodology consists of two phases. In the first phase, the tool and the necessary instruments for its use are designed. Accessibility levels are also established. In the second phase, the tool is applied to a sample size of 45 buildings. The results show the tool and related instruments, as well as the data obtained from the analysis of the sample: identified barriers, the level of accessibility of the entire sample, and the level of accessibility by architectural typologies. The conclusions and discussion reflect on the utility of this tool, the feasibility of its extension to other domains, and the relevance of the information obtained from the sample to improve accessibility in architectural heritage.