As most cities advance in terms of their structures, it has become inevitable for urban planners and city policymakers to be equipped with sophisticated tools. In this chapter, we explore the transformative possibilities offered by large language models (LLMs) as a specific category of help to urban planning. LLMs can be used as effective management of urban data, facilitate decision-making processes, and contribute to more sustainable, just and inclusive structures. The goal is to use such techniques for the maximal suitable allocation of infrastructure, transport, and other public services, fostering cooperation and inclusiveness. In this context, the chapter begins by examining the intricate challenges prevalent in modern urban planning. It then highlights the potential of LLMs and their associated features as transformative assistive technologies. The discussion extends to tracing the evolution of LLMs, including the advancements in neural networks and transformer models that underpin their development. The situations involving the leading models, namely GPT and BERT, allow the chapter to extend to the progress in urban analysis, infrastructure improvement, transport enhancement, and environmental management processes regarding the advances of LLMs. The chapter specifically highlights real-world case studies that demonstrate the application of LLMs in urban planning, while also addressing ethical concerns such as data privacy and algorithmic bias. Furthermore, it explores emerging trends such as smart city development, interdisciplinary collaboration, and the evolution of ethical AI practices, outlining a future landscape of urban environments influenced by LLM technologies.