Step 1: The grid layout: Harappan cities followed a remarkably regular grid pattern, with main streets running north-south and east-west, crossing at right angles and dividing the city into rectangular blocks — an unusually planned layout for the Bronze Age.
Step 2: Citadel and Lower Town division: Most major cities (Mohenjodaro, Harappa) had a distinct division into a raised, walled 'Citadel' (housing large public/administrative buildings) and a larger 'Lower Town' (residential and craft areas), suggesting deliberate zoning by function.
Step 3: Drainage system: Perhaps the most striking feature was the elaborate covered drainage system — nearly every house had its own well and bathing area connected to covered street drains, with inspection holes for cleaning, reflecting a sophisticated concern for public sanitation rarely matched by other contemporary civilizations.
Step 4: Public and private structures: Standardized fired mud-bricks (in a fixed ratio) were used throughout; notable public structures include the Great Bath at Mohenjodaro (probably for ritual bathing) and large granaries for grain storage; houses varied from single-room dwellings to large multi-roomed courtyard houses, indicating some social stratification, though without any single dominating palace structure.
Final Answer: Harappan town planning featured a grid layout, Citadel-Lower Town zoning, standardized brick construction, and an advanced covered drainage/sanitation system unmatched elsewhere in the Bronze Age world.