Explain why archeologists believe that the construction of the earliest Indus Valley cities was carefully planned out. What are the two largest ancient cities that have been discovered in the Indus Valley?

The ruins of two ancient cities, Harappa and Mohenjo-Daro (both in modern-day Pakistan), and the remnants of many other settlements, have revealed great clues to this mystery. Harappa was, in fact, such a rich discovery that the Indus Valley Civilization is also called the Harappan civilization.