There are many Buddhas. Buddha can mean the historical Buddha, who was born Prince Siddhartha Gotama in the foothills of theHimalayas over 2,500 years ago. Or Buddha can mean one who has achieved enlightenment. In this article, I'll give some information about the historical Buddha of this age: Shakyamuni Buddha.
Shakyamuni Buddha, the historical founder of Buddhism, was born in India 3,000 years ago. There are various opinions concerning the exact dates of his birth and death, but according to Buddhist tradition, he is said to have been born April 8, 1029 BC and died on February 15, 949 BC, although other Buddhist scholars place his birth five hundred years later. No definite conclusion has been reached.
Shakyamuni Buddha was the son of Shuddhodana, the king of the Shakyas, a small tribe whose kingdom was located in the foothills of the Himalayas south of what is now central Nepal fifteen miles from Kapilavastu. Shakya of Shakyamuni is taken from the name of this tribe and muni means sage or saint. His family name was Gautama (Best Cow) and his given name was Siddhartha (Goal Achieved) though some scholars say this is a title bestowed on him by later Buddhists in honor of the enlightenment he attained.
So it is evident that many Buddhists observe Buddha's historical birth on April 8, even though the exact date remains in question. Modern archeological and historical research do confirm that Prince Siddartha Gotama lived around this time.
Pilgrimages are made to Lumbini garden, reputedly the site of his birth. An early pilgrim was King Asoka who had much to do with proliferating Buddhism.Taken from: http://www.suite101.com/article.cfm/buddhism/35720