Le Musée du Savon

Tucked right on the Old Port, this museum walks you through the entire history of soap — from prehistoric origins to modern production — using frescoes, rare artifacts, and original documents. It's tied to the Savonnerie de la Licorne, so you're getting the real deal from people who actually make the stuff, not just a sanitized exhibit. Surprisingly absorbing, even if you never thought you'd spend an hour thinking about soap.