Harappan urban planning included the world's first known urban sanitation systems: within the city, individual homes or groups of homes obtained water from wells. From a room that appears to have been set aside for bathing, waste water was directed to covered drains, which lined the major streets. Houses opened only to inner courtyards and smaller lanes. The massive walls of Indus cities most likely protected the Harappans from floods and may have dissuaded military conflicts.[^infrastructure] [^infrastructure]: This is useful for [[Irella]] -- the [[Nahrian People]] probably care more about their walls from the flood protection perspective than as fortifications. ## See Also - [[khanSanitationWastewaterTechnologies]]