The Callwood Rum Distillery is the oldest operating rum distillery in the Caribbean. They've been producing rum at the same location for around 200 years. There is no official tour, but we found a friendly young man who told us about the various rums they produce and we tasted each of them.
Callwood Rum Distillery is located in the Cane Garden Bay area of Tortola, very close to the Glass Studio and the beach. If you are in the area, it is definitely worth the stop. It is like stepping back in time, and it gives you a real appreciation of the history of the island.
FYI - If you'd like to take photos, they ask for a $2 donation.