Union Carbide was a world leader in its field when it built its factory in the heart of Bhopal.
The company went to India with the aim of producing chemicals that would drive an agricultural revolution.
It left a completely different legacy - one of continuing legal battles, claims of criminal negligence.
Many people are still paying a price in terms of health and economic development.
Delnaaz Irani has been talking to survivors and businesses about what happened that night 25 years ago, and how it changed their lives.