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, suggests great the accumulation of great wealth. The city was amazingly well planned with broad main streets and good secondary streets. There were enormous granaries which served as store-houses for the entire community. Finds in excavations of the Mesopotamian civilization indicate that trade flourished between the two civilizations. What is interesting, though, is the total lack of public monuments, obelisks or statues. Moreover, there was no single house which served as a palace, which can be construed as meaning that there were no great inequities in that society, and that a certain democratic spirit prevailed. It appears that merchants might have been individually responsible for safeguarding their wealth from marauding brigands. 

The Indus valley civilization belongs to the Bronze Age. Excellent tools made of bronze (an alloy of copper and tin) have been discovered. They also exported copper, along with peacocks, ivory and cotton textiles in return for silver and other commodities. However, the inhabitants of the various towns and cities in the Indus Valley were essentially farmers, and depended on the periodic floods to irrigate their land. The grain would be collected and distributed at the temple, of which the granary formed a part. Adjacent to the finest group of houses and raised on a 10 metre high platforms are the "citadel" mounds. The Mohenjadaro citadel was a many- roomed building built around a large rectangular tank. This seems to have been used for ritual baths. 

The twin cities of Harappa and Mohenjadaro, which are the two most famous of the Indian Valley civilization sites, are now in Pakistan; both seem to have been built fully planned, and have identical layouts. Neither changed till near the end of the period. Though there was a long period of gradual decay towards 1750 B.C., the actual end was sudden, and remains unexplained though the evidence suggests that the Indus may have changed its course and floods might have followed. Some cataclysmic event, in any case, appears to have struck Harappa, and the cities and town were emptied of their inhabitants. At Mohenjadaro, the city was burnt and the inhabitants killed, and people who were far less advanced than the inhabitants of the Indus Valley seem to have taken possession of the towns. Thus it is possible to argue that the way was paved for the Aryans by the victory of barbarism over an older and more advanced urban culture. 

Sources:

Kosambi, D. D. The Culture and Civilization of Ancient India in Historical Outline. London: Routledge and Kegan Paul, 1965

Thapar, Romila.A History of India, vol I. England: Penguin, 1966