Ancient cities were urban centers that emerged thousands of years ago, often serving as hubs for trade, culture, and governance. Examples include Mesopotamia's Babylon, Egypt's Thebes, and Indus Valley's Mohenjo-Daro. These cities featured advanced architecture, including temples, palaces, and public spaces, reflecting the society's values and beliefs. Many ancient cities were strategically located near rivers or trade routes, facilitating commerce and communication. They often had complex social structures, with distinct classes and specialized labor. The decline of some ancient cities can be attributed to factors like environmental changes, invasions, or economic shifts, leading to their eventual abandonment.