The photo shows a part of ancient DholavIra city, the ancient Indus Valley civilization. excavated in 1967.This is supposed to be built by 2500 BC and is considered as the most valuable discovery of Indian archaeological sites.The photo shows a part of the city's water reserve.It is also seen that this tank is joined by the other tanks on the upper side of it and the opening seen in the front wall is the way for water from these upper tanks.The stone walls and the finishing on them is also seen nicely in the photo.