Buddha-Gayā [Bodha Gayā] The place where Śākyamuni attained Enlightenment. Buddha-Gayā is near the bank of river Nairañjanā in modern Bihar. Earlier the place was known as Urūbilvavana or Uruvelā. It is one of the most sacred places according to Buddhism.

Buddhānusmṛti - A Glossary of Buddhist Terms

Bodhgayā

Modern Indian name for Buddha-gayā, the site of the Buddha's enlightenment (bodhi) on the banks of the river Nairañjanā, a southern tributary of the Ganges, near ancient Rājagṛha. It was here that the seat of enlightenment (bodhimaṇḍa) was located, as well as the Bodhi Tree under which the Buddha Śākyamuni had sat. Though the Bodhi Tree was damaged on a number of occasions, the present tree is said to have grown from a cutting of the original tree. The Mahābodhi Temple at Bodhgayā was begun during Aśoka's period but repeatedly rebuilt and expanded over the centuries. It still received patronage for its upkeep as late as the 13th century ce, from the rulers of Burma. By the 16th century, the deserted and ruined building was taken over for a while by Śaivite followers. It was eventually restored as a Buddhist site by the Burmese in the early 19th century ce, though it was later taken over by Hindus. The 1949 Bodhgayā Act ensured that this important site was once again given full recognition as a Buddhist holy place.

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)