What was one of the most impressive things about the ancient cities of Harappa and Mohenjo-Daro?

Despite the many unknowns, the Dravidian culture was at a very high level, and the urban perfect cities along the Indus  Mohenjo-Daro and Harappa rivers stood out in particular.

Explanation:

The layout of the main streets was planned and cut at right angles.The houses of the wealthier had bathrooms and landscaped yards, complex covered sewage systems with openings and septic tanks and public wells were evidence of the high hygienic conditions prevailing in the mentioned cities. In addition, there were large public bathrooms for the poorer, who could not afford to build their own bathroom in their home.