Final answer:
Harappa and Mohenjo-Daro were central cities in the Indus Valley civilization, known for advanced urban planning and architecture, including multistory houses with plumbing. These cities had complex social structures with extensive public amenities but declined due to environmental issues.
Step-by-step explanation:
The ancient cities of Harappa and Mohenjo-Daro were prominent urban centers of the Indus Valley civilization, renowned for their sophisticated urban planning and architectural prowess. These archaeological sites suggest a population of about thirty thousand inhabitants each at their zenith. Well-laid-out streets in a grid pattern indicate some degree of centralized control or shared urban planning principles across the valley. Residential areas displayed remarkable features such as wells in homes for running water, and multistory buildings, demonstrating a high standard of living and advanced technological capabilities for their time.
Social structures seemed complex with evidence of labor specialization, urban management, and coordination necessary for irrigated agriculture without clear signs of a dominant centralized state. The cities boasted extensive public facilities, including large public baths and granaries indicating an organized society with a focus on public welfare and religious rituals. Cultural aspects included the use of standard weights and measures, ceremonial baths, and symbolic motifs, influencing subsequent Indian civilizations. However, environmental degradation likely played a pivotal role in the eventual decline of these urban centers around 1700 BCE.