it is famous as it is the place where Gautama Buddha is said to have obtained Enlightenment (Pali: bodhi) under what became known as the Bodhi Tree.
For Buddhists, Bodh Gaya is the most important of the main four pilgrimage sites related to the life of Gautama Buddha, the other three being Kushinagar, Lumbini, and Sarnath. In 2002, Mahabodhi Temple, located in Bodh Gaya, became a UNESCO World Heritage Site.
Bodh Gaya is the most holy place for Buddhists. Situated by the bank of river Neranjana the place was then known as Uruwela. King Ashoka was the first to build a temple here.
Traditionally, Buddha was born in 563 BC in what is now Nepal on the following auspicious Baisakhi purnima. As Siddhartha, he renounced his family at the age of 29 in 534 BC and travelled and meditated in search of truth. After practicing self-mortification for six years at Urubela (Buddhagaya) in Gaya, he gave up that practice because it did not give him Vimukthi. Then he discovered Noble Eight-fold path without help from anyone and practiced it, then he attained Buddhatva or enlightenment. Enlightenment is a state of being completely free from lust (raga), hatred (dosa) and delusion (moha). By gaining enlightenment, you enter Nibbana, in which the final stage is Parinibbana.
At this place, the Buddha was abandoned by the five men who had been his companions of earlier austerities. All they saw was an ordinary man; they mocked his well-nourished appearance. "Here comes the mendicant Gautama," they said, "who has turned away from asceticism. He is certainly not worth our respect." When they reminded him of his former vows, the Buddha replied, "Austerities only confuse the mind. In the exhaustion and mental stupor to which they lead, one can no longer understand the ordinary things of life, still less the truth that lies beyond the senses. I have given up extremes of either luxury or asceticism. I have discovered the Middle Way". This is the path which is neither easy (a rich prince) nor hard (living in austere conditions practicing self-denial). Hearing this, the five ascetics became the Buddha's first disciples in Deer Park, Sarnath, 13 km n.e. of Benares.
The disciples of Gautama Siddhartha began to visit the place during the full moon in the month of Vaisakh (April–May), as per the Hindu calendar. Over time, the place became known as Bodh Gaya, the day of enlightenment as Buddha Purnima, and the tree as the Bodhi Tree.
The history of Bodh Gaya is documented by many inscriptions and pilgrimage accounts. Foremost among these are the accounts of the Chinese pilgrims Faxian in the 5th century and Xuanzang in the 7th century. The area was at the heart of a Buddhist civilization for centuries, until it was conquered by Turkic armies in the 13th century. The place-name, Bodh Gaya, did not come into use until the 18th century CE. Historically, it was known as Uruvela, Sambodhi, Vajrasana or Mahabodhi. The main monastery of Bodh Gaya used to be called the Bodhimanda-vihāra (Pali). Now it is called the Mahabodhi Temple.
Five bombs were detonated in Mahabodhi temple premises on 7 July 2013. 4 bombs were also detonated in town while three were defused.
Refernce: https://en.wikipedia.org/wiki/Bodh_Gaya