St. John the Baptist Fort, Fortaleza São João Baptista in Potuguese, is a great place to introduce kids to Ibo's colonial history. Built by the Portuguese in 1791, this pentagonal fort overlooking the island's harbor was erected on mudflats to protect the island's narrow shipping channel. The fort was later used as a prison as well as holding place for slaves. Take note of the cannons as well as the small chapel inside. Watch local craftsman fashion old metacais into filigree jewelry.