The Museu do Douro is housed in the 18th-century Casa da Companhia Geral, the original administrative headquarters of the wine company set up by the Marquis of Pombal to regulate port production. The building itself is worth visiting — vaulted cellars, river-facing stone facade — and the permanent collection runs through the history of the demarcated region from the 1750s onward.
Allow ninety minutes. The film at the start gives the best overview of how the schist terraces were built by hand over centuries, and the upstairs galleries cover everything from port shipping to the rabelo boats to phylloxera. The shop has an excellent selection of wines from small producers that you would struggle to find outside the valley.