Belum Caves, Limestone caves in Nandyal district, India

Belum Caves forms an underground limestone cave system extending over three kilometers, composed of several connected galleries and chambers. The cave displays numerous formations created by mineral-rich water dripping slowly over thousands of years, with stalactites hanging from the ceiling and stalagmites rising from the floor, alongside natural columns where the two meet.

Belum Caves were long known to local inhabitants but first documented scientifically in 1884 by British geologist Robert Bruce Foote. A German speleological team led by Herbert Daniel Gebauer explored and mapped the system between 1982 and 1984, assisted by three local men, Ramaswamy Reddy, Chalapathi Reddy and Maddileti. Andhra Pradesh declared the caves a protected site in 1988, and they opened to visitors in 2002. Excavations recovered pottery dated to 4500 BCE, and Buddhist and Jain ascetics later used the chambers.

The name may derive from bilam, meaning a pit or hole, later softened to Belum. Local guides name formations after their shapes: Kotilingalu, a chamber of stalactites resembling Shiva lingams, and Saptasvarala Guha, where struck stalactites sound musical notes, opened to visitors in 2006. A naturally formed Shiva lingam is treated with devotion.

The temperature inside the cave remains around 15 degrees Celsius (59 degrees Fahrenheit) throughout the year, so bringing a light jacket or sweater is advisable. Sturdy shoes with non-slip soles are recommended, as some sections of the pathway can be damp and uneven.

The Simhadwaram is a natural arch of stalactites shaped like a lion's head, not a reclining lion. In the Saptasvarala Guha, or Musical Chamber, opened to visitors in 2006, the stalactites sound like music when struck with a stick or fingers. The blind isopod Andhracoides gebaueri was found in the Pataalaganga chamber and named after Herbert Daniel Gebauer in 2015.