What civilization made the water tank and citadels?

The civilization known for constructing water tanks and citadels is the Indus Valley Civilization, which thrived around 2500 BCE in present-day Pakistan and northwest India. They built sophisticated urban centers, such as Mohenjo-Daro and Harappa, featuring advanced drainage systems and large public baths, indicating a high level of engineering and urban planning. The citadels served as administrative and religious centers, highlighting their organizational skills and societal structure.