Digital transformation in the public sector describes the shift from traditional creation and delivery of services, into the massive use of digital technologies to enhance public services. The digitalisation of public administration presents significant challenges for many municipalities in the social, economic, environmental, and sustainable dimensions. Cities take advantage of the rapid advances in information and communication technologies capabilities to make the provision of city services (e.g., health service, transport service, air-quality service, education service) more efficient. These modern urban environments are commonly referred to as Smart Cities, where advanced and innovative services are offered to improve the overall quality of life for the citizens. Smart Cities are complex systems that involve diverse stakeholders and concerns, use heterogeneous information systems and technologies, and aim to fulfill multiple and conflicting goals. Such complexity challenges the provision of services that may fail to achieve city goals and meet the needs of citizens due to the lack of alignment between city services and the information systems that support them. Evidence of this is the existence of city services and systems that fail to address the real needs of stakeholders, and are not perceived as valuable by them because they do not interoperate, leading to duplication of work and incompatible solutions. Enterprise Architecture (EA) is an established planning and governance approach to manage the complexity of corporate systems. EA presents a holistic view of organisational business strategies and IT initiatives to achieve organisational goals by adopting a comprehensive perspective on the overall architecture. Smart Cities can be seen as urban enterprises with more complex and multi-dimensional systems that require integration among smarter services from different domains (e.g., mobility, energy, public safety, emergency, education, culture, etc.) to respond to diverse interests and objectives from a range of stakeholders. Existing research on EAs for Smart Cities uses the concept of layers and views to describe architecture content and guide its implementation. However, these approaches do not identify the concepts to describe and model the relationships between the service and information layers which are essential to address the strategic alignment. Furthermore, there is an absence of such concepts in languages and metamodels for Enterprise Modelling. These architectures and metamodels mostly emphasize technical aspects that constitute Smart Cities and they rarely focus on city services and their strategic aspects towards delivering the cities vision and objectives. This research introduces ArchiSmartCity, a metamodel that addresses the alignment between city services and information systems according to Smart City strategies to assist in the digitalisation of public city services. In this thesis, design principles and design requirements are defined and instantiated by designing the ArchiSmartCity metamodel that explicitly expresses this alignment, following a design science research approach. Further, ArchiSmartCity is developed and implemented as a coherent extension of an EA metamodel to describe an expository instantiation and its application. ArchiSmartCity is evaluated in an iterative manner within multiple-case studies, by creating real-world services models that are validated by Smart City domain experts. Moreover, this thesis demonstrates and evaluates ArchiSmartCity by developing a computer-based solution for semantic alignment analysis. Ex-post evaluation results demonstrate the quality and practical relevance of the developed metamodel extension for cities and municipalities. This study contributes to the current understanding of how city strategies should be aligned with Smart City implementations by providing a prescriptive view and metamodel to guide coherent and unambiguous architecture design in the Smart Cities field.