Step 1: Understanding the Concept:
The Dharmachakrapravartana Sutra (Setting the Wheel of Dhamma in Motion) marks the beginning of the Buddhist Sangha and the first public teaching of the Four Noble Truths.
Step 2: Detailed Explanation:
After attaining enlightenment at Bodh Gaya, the Buddha walked to the Deer Park in Sarnath, near Varanasi.
There, he met his five former ascetic companions and delivered his first sermon.
- Lumbini: Birth.
- Bodh Gaya: Enlightenment.
- Kushinagar: Death (Parinirvana).
Step 3: Final Answer:
The first sermon was delivered at Sarnath.