The Dhammacakkappavattana Sutta is the Buddha's first discourse after he
reached
Enlightenment. In this sutta, the Buddha discusses the Middle Way, the Noble
Eightfold
Path and the Four Noble Truths. (http://en.wikipedia.org)
Dhammacakkappavattana Sutta
http://www.accesstoinsight.org/tipitaka/sn/sn56/sn56.011.than.html
Anattalakkhana Sutta
http://www.accesstoinsight.org/tipitaka/sn/sn22/sn22.059.than.html
About Sarnath
http://en.wikipedia.org/wiki/Sarnath