Harappa is 4700 years old city in the subcontinent, discovered in 1920. After its discovery cities like Mohenjodaro, Lothal, Dholavira and Kalibangan have also been discovered and are known as the Harappan cities as were discovered after Harappa.
All these cities were discovered around river Indus and hence prove the existence of the Indus Valley Civilization.
The city of Harappa was divided into a citadel and a lower town. The citadel was smaller but higher and was located on the west than the lower town located on the east. The citadel comprised granaries, religious buildings, public buildings and assembly halls while the lower town was divided in rectangular sections cut by wide roads at right angles to each other.
People built one or two story houses on either side of the roads with rooms built around a courtyard. The Harappan city had a well-planned drainage system where every house had a drain connected to the street drains which further were connected to the bigger drains. The drains were covered with stone slabs and laid in straight lines with inspection holes for cleanup.
The different Harappan cities had unique characteristics. Dholavira was divided in a citadel, middle town and a lower town unlike the others. Mohenjodaro had the Great Bath surrounded with rooms on all sides. It had stairways on the northern and the southern end, with walls layered with natural tar.
Mohenjodaro, Harappa and Lothal also had huge store houses used for storing grains and hence were called granaries. Big fire altars are found at Kalibangan and Lothal used for performing sacrifices. Lothal, also has revealed a huge dockyard for loading and unloading of goods.