Smart Cities have become one of the most interesting research topics for governments, businesses and researchers in the last few years. Being a Smart City implies a competitive edge compared to other cities in terms of economic growth, sustainability, human resources and governance. Therefore, more and more governments pursue this future vision and hop onto the Smart City `Bandwagon'. However, the development of Smart City solutions is faced with challenges since there is no clear definition for Smart Cities yet. This paper provides a review on what challenges arise when designing Smart City solutions to provide a complete overview of identified challenges. This paper carries out a systematic literature review of publications between 2008 and 2016 which will be compared with a field study on Smart City initiatives conducted by the municipality of Enschede to develop a requirements framework for these projects. This research is relevant to governments and businesses aiming to create Smart Cities and for researchers, who aim to enhance the concept of Smart Cities. This paper found eight sub-domains within the topic of Smart Cities and these are: Technical Infrastructure, Application Domains, System Integration, Data Processing, Governance & Management, Society & Citizens, Business Domain and Environmental Sustainability. The eight sub-domains are respectively divided in two types: technological and non-technological domains. By firstly identifying the challenges and their solutions within these sub-domains, this paper proposes a requirements framework in combination with a checklist of questions to provide guidance for promoters to conduct future initiatives.