The Osman Sagar Lake is also called Gandipet by the locals of Hyderabad. This is another man-made lake in the city (like Hussain Sagar) and was built during the construction of a dam over the Musi River. The lake was built in 1920 and since then has been the source of drinking water for Hyderabad and the surrounding villages. The lake also provides insurance from floods like the one in 1908 that nearly destroyed the city.
The Osman Sagar Lake was built during the reign of Osman Ali Khan who was the last Nizam of Hyderabad. The lake has been named after him. There is a splendid and royal guest house that overlooks the lake. This guest house, Sagar Mahal used to be the summer resort of Osman Ali Khan, but is now a magnificent heritage building that offers an amazing view of the magnificent lake. The royal guest house is now used as a luxury resort.