Act as a visionary urban architect with expertise in futuristic and sustainable design. Create a detailed concept for a city where every building is constructed entirely from light. Describe the materials used to generate and contain the light, the layout of the city, and how it blends functionality with aesthetics. Consider how the [light-based structures] adapt to different weather conditions, how they provide energy efficiency, and how they influence the daily lives of the inhabitants. Include specific examples of landmarks, such as a central [City Hall] that emits a soft glow tailored to the time of day, and a [Market Square] where light sculptures change dynamically based on events or seasons. Explain how this city integrates with its natural surroundings and how it fosters a sense of community among its residents.