A megacity is formally defined as a metropolitan area with a total population exceeding 10 million people. The number of such cities has grown at an unprecedented rate in recent decades. While cities like New York and Tokyo were among the first, the most rapid expansion of megacities is now occurring in developing nations across Asia, Africa, and Latin America. This phenomenon is driven by factors such as rural-to-urban migration and high birth rates. This rapid urbanization presents substantial challenges. The immense population density puts a severe strain on existing infrastructure, including transportation, sanitation, and housing. Furthermore, environmental concerns are paramount; high levels of energy consumption and industrial activity contribute to air and water pollution, while the loss of natural habitats is a frequent consequence. Addressing these issues requires innovative approaches to urban planning and a firm commitment to sustainability to ensure that these cities are livable for future generations.