The Iberian Museum of Masks and Costumes occupies a handsome building in Bragança and holds a genuinely unusual collection: hundreds of masks and festival costumes from Portugal, Spain, and other parts of the Iberian Peninsula and beyond. Many of the masks are the terrifying carved-wood or metal faces used in the midwinter Carnival festivals of Trás-os-Montes — grotesque, colourful, and very old in spirit.
The collection is well presented and explained (in Portuguese and English), with context about the festivals and their social function. This is not a dusty ethnographic cabinet but a thoughtful display of objects that are still in use in living communities. Bragança is a good place to learn about this tradition because the villages where it survives are just to the south — if your visit coincides with Carnival in February, you may be able to see the masks in action.