Indus Valley Civilization was one of the world's oldest and greatest civilizations which took shape around 3000 BC to 2500 BC in the valley of the Indus River. Remains of more than 100 cities, towns, and villages of the Indus Valley civilization have now been found from north of the Hindu Kush down the entire length of the Indus and beyond into peninsular India. Harappa and Mohenjo Daro are the two urban centers of Indus Valley civilization and the excavation of these sites reveal standardization and ordered society and ten centuries of relatively stable conditions.
The city was amazingly well planned with broad main streets and good secondary streets. The houses of these cities were solidly built of bricks and many were multi-storied and equipped with bathrooms and lavatories. The high quality of the pottery, along with hoards of gold and silver found at Indus Valley sites, suggest great accumulation of wealth. Each city was laid out on a grid plan with a high citadel and a lower city of domestic dwellings. Urban planning is evident in the neat arrangement of major buildings contained in the citadel, including the placement of a large granary and water tank or bath at right angles to one another. The lower city, which was tightly packed with residential units, was also constructed on a grid pattern consisting of a number of blocks separated by major cross streets. The cities had an elaborate public drainage system. Sanitation was provided through an extensive system of covered drains running