Being one among the five largest Harappan cities in the subcontinent, Dholavira has yielded many firsts in respect of Indus civilization. Fourteen field seasons of excavation through an enormous deposit caused by the successive settlements at the site for over 1500 years during all through the 3rd millennium and unto the middle of the 2nd millennium BC have revealed seven significant cultural stages documenting the rise and fall of the Indus civilization in addition to bringing to light a major, a model city which is remarkable for its exquisite planning, monumental structures, aesthetic architecture, amazing water harvesting system and a variety in funerary architecture. It also enjoys the unique distinction of yielding an inscription made up of ten large-sized signs of the Indus script and, not less in importance, is the other find of a fragment of a large slab engraved with three large signs. This paper attempts to give an account of hydro-engineering that is manifest in the structures of the Harappans at Dholavira. The ancient site at Dholavira (230 53' 10" N; 700 13'E), taluka Bhachau, district Kachchh in state Gujarat, lies in the island of Khadir which, it turn, is surrounded by the salt waste of the Great Rann of Kachchh. The ancient settlement is embraced by two monsoon channels, namely, the Manhar and Mansar. The ruins, including the cemetery covers an area of about 100 hectares half of which is appropriated by the articulately fortified settlement of the Harappans alone. The salient components of the full-grown cityscape consisted of a bipartite 'citadel', a 'middle town' and a 'lower town', two 'stadia', an 'annexe', a series of reservoirs all set within an enormous fortification running on all four sides. Interestingly, inside the city, too, there was an intricate system of fortifications. The city was, perhaps, configured like a large parallelogram boldly outlined by massive walls with their longer axis being from the east to west. On the bases of their relative location, planning, defences and architecture, the three principal divisions are designed tentatively as 'citadel', 'middle town', and 'lower town'.