Cumbum, a town in Prakasam district of Andhra Pradesh, is widely popular for the age-old man-made lake here. Also called Gundlakamma Lake, it is built on the rivulet of the same name upon Nallamalai Hills. The lake is 7km long and has a width of 3.5km. The town is the headquarters of Cumbum mandal in the Markapur Revenue Division.

Cumbum Lake is touted as one of the oldest man-made lakes in Asia. It has its roots in history as it was built by Gajapati rulers of Odisha back in 15th century and was later modified and its anicut was built by Varadharajamma, Vijayanagar princess and wife of King Krishnadevaraya back in 17th century. Details provided from the Imperial Gazette of India shows that in those days, the lake supplied its water to 10,300 acres of land for the purpose of irrigation. No wonder that it earned the reputation of being the second-largest irrigation tank in Asia.