Inside the Torre de Belém, Mindelo's most intriguing museum gives an overview of São Vicente's history, from the island's role in the triangular trade to whaling in the late 19th century. Displays from shipwrecks reveal intriguing finds like 200-year-old bottles of port wine (still sealed) and massive elephant tusks (a jaw-dropping 820 tusks were logged on the 1743 wreck of the Princess Louisa).
Take the spiral staircase from the top floor to open-air views over sea and mountains.