Rum Museum - Havana Club Fundation. You can't go to Havana without visiting the Museo del Ron. The Havana Club Foundation was opened on March 31st, 2000. Its set in an 18th Century Palace and It is a cultural and tourist complex created by Havana Club International s.a.
You can sign up for a guided tour (in your language) and go through a replica distillery. There are scale models of the process of making rum, replica rooms and machines, etc.
After the tour, you go to a bar and get free samples. Also there is a great little gift shop where you can get rum, glassware, shirts, etc.