São Sebastião is a small fort that houses the national museum, a few rooms of artifacts simply presented. The eclectic, somewhat decaying collection, in Portuguese, covers the country's entire history, but manages to inspire a feeling of what life was like in colonial times. It's also the only history museum in the country. A knowledgeable guide would add a lot here, but you'll have to bring your own (contact Navetur). Ring the bell if no one is around.