There are four supremely sacred places to the Buddhism religion, Buddha went to these places in his life journey each marking a crucial moment in his life. There are the locations of his birth, enlightenment, first sermon and his death. They have all had temples built on top of them.
Lumbini is in the Himalayan mountains of Nepal. This is Buddhas birthplace. He was the son of the chieftain of the Sakya clan.
Bodh Gaya is in Bihar India. This is were he obtained ultimate enlightenment. It is said that he sat under a pipal tree until he obtained ultimate enlightenment.
Sarnath is in Uttar Pradesh, India. It is were Buddha mad is first sermon. A sermon is a religious instruction. He talked about avoiding extremes when trying to find spiritual peace.
Kushinara is also in Uttar Prades, India. It is where Buddha died it was 45 years after his first sermon. His death referred to the Buddhist belief Mahaparinirvana, or "the great passing away".