Osman Sagar is also known as `Gandipet`. It is an excellent picnic spot with well-laid gardens. Osmansagar is one of the two lakes on the city`s periphery that supplies drinking water to the great metropolis.
The lake is a reservoir created by a dam across the Isa, a tributary of the River Musi. It was constructed by Mir Osman Ali Khan, the VIIth Nizam of Hyderabad after the disastrous floods of 1908 by constructing a dam across river Musi. Mokshagundam Visweswarayya planned the lake for supplying water to the city of Hyderabad. The lake is spread over an area of 46 square kilometers. It has well laid out lush green gardens and a swimming pool. It is a very popular picnic spot for the city crowd.Overlooking the lake is the heritage building, Sagar Mahal, built as a resort by the Nizam of Hyderabad and converted now into a lake resort managed by AP Tourism.