Located in the ancient city of Chiang Saen in Chiang Rai, the Opium House Museum is a small museum dedicated to displaying the history of opium production in the northern region of Thailand. poppy into morphine which is then converted into heroin; It is an illegal drug, and throughout history, locals in northern cities made money selling illegal drugs and unfortunately became addicted to them. In this museum, you can learn about how illegal drugs are made, used and distributed, and you will be able to see the unfortunate life of local people who have become drug addicts and the money they get from selling illegal drugs all over the world.