Belum Caves is the second largest cave in Indian sub-continent and the longest caves in plains of Indian Subcontinent. It lies in Kurnool district of Andhra Pradesh. Belum Cave is 3.5 km in length and the second longest cave in India next to 21km long Krem Um Lawan cave in Meghalaya. Belum Caves derives its name from "Bilum" Sanskrit word for caves. In Telugu language, it is called Belum Guhalu. The caves are a collective array of subway passages that were first discovered in 1854.They have long passages, spacious chambers, fresh water galleries and siphons. All this makes Belum Caves a geological & archeological attraction worldwide. A thrilling experience indeed, the tourist while visiting the out-of-the-world Belum Caves, can cherish the splendid beauty of the surrounding ambience which is accompanied by an air of serenity.
To discover the unexplored treasures of the Belum Caves, the archeology and museum department along with the European Cave researchers, have carried out extensive exploration works in the place. Proofs of ancient civilization are found in these natural Caves that have eventually helped in making the place one of the prime spots of historical importance and tourist attraction.There are indications that Jains and Buddhists monks were occupying these caves centuries ago. Many Buddhists relics were found inside the caves. These relics are now housed in Museum at Ananthapur.There is a giant Buddha Statue near a hillock near the Belum Caves. The area of cave known as "Meditation hall" was used by Buddhist Monks.An interesting formation at Meditation hall looks like a bed with pillow to recline. The local legend has it that in ancient times many sages use to live here. The relics of Buddhist period were found here.Archaeological survey of India (ASI) also found remnants of vessels, etc. of pre-Buddhist era and has dated the remnants of vessels found in the caves to 4500 BC.
The Belum Caves are facilitated by three natural opening points that are in the shape of a well. The interiors of the Caves are an enticing view of splashing fresh water corners, wide compartments and stretched out passageways. One of the unique touristy attractions of the state, the entire area inside the Caves covers a total of 3229 meters. The visitors have to cover a sloping passage (by a staircase down a sinkhole) of 20 meters to reach to the main cavity of the Caves.Most of the cave system is developed at this level, and the tour path is rather level from now on, following the main passage, except for a few places.The novelty of the cave and the immense advertisement resulted in a real rush to the cave. In the first six months the cave was visited by more than 60,000 people, and each Sunday 3,00 people visit the cave. Only 2km of the Belum Cave is opened for public. To enter inside the cave one should be accompanied by a guide and freely wandering in the cave is strictly prohibited. There are three entry points to the cave out of which one is converted to a main entrance.Andhra Pradesh Tourism Development Corporation (APTDC) has developed the pathways in around 2 km of the length of the caves, provided soft illumination and has created fresh-air-shafts in the caves. At many places inside the cave, APTDC has installed bridges, staircase, etc. for easy movement inside tha cave. It has also created a canteen, washroom and toilet facilities near the entry point. The APTDC also arranges excellent lighting for the caves. There are passages in the cave where one will have to crawl to pass by. There are some streams inside the cave. There is a chamber inside the cave where a lot of stalactites and stalagmites (horn like formation of limestone) can be seen.This section contains stalactite formations which are akin to shiva lingams. This section has thousands of such stalactite giving it a surrealistic look. It has one huge pillar formed due to stalactite and stalagmite joining together. The chamber is called Kotilingalu and the entrance to chamber is called Simhadwaram.Simhadwaram is another attratction inside the cave. It means lions gate. It is a natural arch of stalactites formed in the shape of a lion’s head. There is a chamber inside the cave called Saptasvarala Guha or Musical chamber where the limestone formations make metallic sounds.Saptasvarala Guha or Musical chamber was recently discovered. Not really special, as all stalactites on earth sound like this when hit with a wooden stick or the finger knuckles. 
As it is uncommon for foreign tourists to visit the caves on their own, the APTDC offers package tours for Ahobilam, Alampur, Mahanandi, Srisailam, Mantralayam and other places. The one day trips by coach include the coach ride, the cave visit and other sights.