The Indus civilization or the Harappan civilization, which flourished during the Bronze Age i.e. 2500-2000 BC is ranked among the four widely known civilizations of the old world. Extensive excavation work that has been done since Independence has so far identified more than 100 sites belonging to this civilization. A few prominent among them are Dholavira (Gujarat), Kalibangan (Rajasthan), Lothal (Gujarat), Sarkotada (Gujarat), Diamabad (Maharashtra), Alamgirpur (U.P.), Bhagwanpura (Haryana), Banawali (Haryana), Kuntasi, Padri (Gujarat) and Mauda (Jammu). Extensive town planning was the characteristic of this civilization, which is evident from the gridiron pattern for the layout of cities, some with fortifications and the elaborate drainage and water management systems. The houses were built of baked bricks, which is rare in contemporary civilizations at Mesopotamia and Egypt. Bricks of fixed sizes, as well as stone and wood were also used for building. Buildings in the lower area are rather monotonous, being mainly functional rather than decorative. But many houses are two storeyed. The most imposing of the buildings is the Great Bath of Mohenjodaro. It is 54.86 metres long and 32.91 metres wide and with 2.43 metres thick outer walls. The Bath had galleries and rooms on all sides. Another important structure was the Granary complex comprising of blocks with an overall area of 55 x 43 metres. The granaries were intelligently constructed, with strategic air ducts and platforms divided into units.