After Mohenjo-daro was excavated they found that the city had been rebuild on top of itself a few times. They theorise that it got flooded when the Indus river

After Mohenjo-daro was excavated they found that the city had been rebuild on top of itself a few times. They theorise that it got flooded when the Indus river left it's banks. They just added more bricks to the walls and the city got higher. From what I remember looking at the ruins it happened 3 or 4 times and some of the walls were 3+ stories tall. It's weird to think that 3-4 thousand years ago they build bulidings that survived floods but we are still not able to .