The Nagarjuna Sagar Dam on River Krishna is considered to be the largest stone masonry dam in the world. Around 150 km from Hyderabad, with a catchment of 2,15,000 sq km, it has the most widely spread canal system in India. Completed in 1969, the 124-m-high dam is one kilometre long and has 26 crest gates. Its reservoir can store up to 11,472 million cubic meters of water. It is one of the first projects built for the purpose of generating hydro-electricity after India gained Independence. A lake has been built behind the dam, which is one of the largest man-made lakes in the world. With beautifully landscaped gardens surrounding it, the lake makes for an ideal picnic spot in winter. It is also a popular site for boating. A little ahead is Nagarjunakonda, a small hillock and island (from which the dam draws its name) with a Buddhist museum, which has exhibits dating back to the 3rd century. Just 22 km from  Nagarjunakonda are the Ethipothala Waterfalls and Srisailam Wildlife Reserve.