# Metaverse Meets Smart Cities--Applications, Benefits, and Challenges
## 4 Materials and Methods  
The study focuses on evaluating the metaverse's application potential in the smart city context. A systematic approach has been applied, combining different research methods, particularly qualitative and inductive approaches. This research aims to develop a comprehensive understanding of the metaverse's areas of application and identify concrete potential applications. The insights gained were validated through real-world examples and considered in terms of potential smart city applications and their technological requirements.  
The first phase of the research involved extensive qualitative literature and internet research to create a list of relevant application areas in the context of the metaverse. The literature research was carried out to provide a comprehensive basis for understanding the current knowledge about the smart city metaverse and identify potential applications. The online literature databases Google Scholar, Scopus, and Web of Science were searched with the search terms \"Smart City Metaverse\", \"Urban Metaverse\", \"Municipality Metaverse\", \"Metaverse City Applications\", and \"Metaverse Risks Challenges\". The search included peer-reviewed journal articles, as well as articles in books and conference contributions, in order to consider a wide range of relevant sources.  
The first ten results per search term were analyzed to ensure a balance between completeness and manageability of the literature review. Of the 146 suggested articles, 112 unique results remained after removing the duplicates. Upon closer examination of these results, 19 studies were relevant to the research focus. Special attention was paid to current publications published within the last five years and with a high number of citations to ensure that the information collected is up to date and has a significant impact on the scientific community.  
To identify already existing applications in the urban environment, in addition to the scientific sources, various online sources were used to identify an extensive portfolio of different applications. The non-scientific online sources were researched via the search engine Google with the search terms \"Metaverse application city\", \"Metaverse application smart city\", \"Metaverse smart city\", \"Metaverse citizen\", and \"Metaverse real application\". Results were only considered if at least three independent sources equally described them. In addition to the literature research, three expert interviews were conducted to complete and compare the identified applications and challenges. For this purpose, three experts from different industries who are publicly active in the field of the metaverse were chosen. The first expert is a research executive at a university metaverse lab. Expert two supervises metaverse industry projects as head of development. The third expert is the chief marketing officer at a company that deals with blockchain, NFTs, and 3D models for the metaverse. The experts were intentionally selected from different industries to cover different perspectives and requirements.  
The research methods provided a thorough approach to studying the smart city metaverse and its applications. An extensive search of literature databases and consideration of recent publications within the last five years ensured that the information gathered was up to date and significantly influenced the scientific community. Including non-scientific sources via online search engines complemented the literature search to capture a comprehensive portfolio of different applications. Interviews with experts from different industries provided practical insights and enabled the consideration of different perspectives and requirements. The results from the literature review and expert opinions were combined to create a complete picture of the potential applications and challenges associated with the smart city metaverse. These methods were chosen to capture a broad range of information and provide a sound basis for the scientific work.