"Design a futuristic, sustainable city with a population of 2 million people, organized in a radiocentric layout with a monumental central building at its heart. The central building serves as the core of governance, business, and transportation. Surrounding the central building, the city is divided into five concentric rings, each with a specific function and character. The first ring, closest to the center, features high-density residential buildings, commercial districts, hospitals, and educational institutions. The second and third rings consist of medium-density residential areas with apartments, parks, local markets, and recreational spaces. These rings are designed for easy access to daily needs, with everything located within walking distance. The outer two rings have low-density housing for families, with larger homes, green spaces, and smaller local commercial hubs. The city operates with zero private cars. Instead, a state-of-the-art underground metro system runs beneath the city, connecting all five districts. The metro stations are integrated into the central building and throughout the city, with modern, sleek trains moving efficiently between districts. Above ground, the city has extensive pedestrian paths and bike lanes for eco-friendly transportation. The buildings are constructed with eco-friendly materials, featuring solar panels, green roofs, and vertical gardens, ensuring the city remains energy-efficient and sustainable. The urban design prioritizes nature, with lush green parks surrounding each district and nature reserves on the outskirts. Every district is equipped with large public squares, where people can gather, socialize, and engage in cultural activities. These spaces are surrounded by modern, eco-conscious architecture and are seamlessly integrated with nature. The city's public spaces are designed to foster a sense of community, sustainability, and well-being, offering residents a comfortable, efficient, and green living environment. In this city, sustainability, technology, and nature coexist harmoniously to create a thriving, eco-friendly urban environment."