The Hirakud Dam is a composite structure of earth, concrete and masonry. 10 km (6.2 mi) north of Sambalpur, it is the longest major earthen dam in India, measuring 25.8 km (16.0 mi) including dykes, and stands across the river Mahanadi. The main dam has an overall length of 4.8 km (3.0 mi)[2] spanning between two hills; the Laxmidungri on the left and the Chandili Dunguri on the right. The dam is flanked by 21 km (13 mi) of earthen dykes on both the left and right sides, closing the low saddles beyond the adjoining hills. The dam and dykes together measure 25.8 km (16.0 mi).[2] It also forms the biggest artificial lake in India,[dubious – discuss] with a reservoir holding 743 km2 (287 sq mi) at full capacity, with a shoreline of over 639 km (397 mi). There are two observation towers on the dam one at each side. One is "Gandhi Minar" and the other one is"Jawahar Minar". Both the observation towers present extensive views of the lake.