Smart cities emergence has allowed a wide variety of technological services to metropolitan areas. These services can improve life quality, minimize environmental impacts, improve health service, improve security, and bear the increasing number of people in the cities. Life quality encompasses many subjects, and accessibility for People with Disabilities (PwD) is one. In this article, smart cities focused on helping PwD are called Assistive Smart Cities (ASCs). In this sense, the article proposes a Model for Assistive Smart Cities called MASC. Related works do not cover geographically broad areas, such as cities and metropolitan regions. Moreover, they are not generic in terms of disabilities and are usually intended only for one type of disability. Given this scenario, the MASC covers large regions and supports various disabilities, such as hearing, visual impairment, and limitation of lower limb movements. Unlike the related works, MASC uses the interactions of PwD to compose histories of contexts offered as services. MASC proposes an ontology-based on ubiquitous accessibility concepts. The model evaluation focused on performance, functionality, and usability. Performance and functionality evaluations were performed using data generated by a context simulator called Siafu and data from the Open Street Maps (OSM) platform. Usability was evaluated using a smart wheelchair prototype. The results of usability show 96% acceptance regarding ease of use and 98% regarding system utility. The results indicate that the model supports massive applications, managing information to generate trails. Besides, MASC provides services for different types of users, namely PwD, healthcare professionals, and public administration.