This map shows the fort on Das Cobras Island, near Rio de Janeiro. The title of the map–“Map of the Fortress of Cobras Island Built to Harass Ships that Anchor in the Harbor”–is taken from the note in the lower right, and indicates the role that the fort played in defending the harbor. The first fort was erected on the island in the 1620s, when Portugal’s Brazilian holdings were under threat from the Dutch as well as from the French and the English. Over the next century, the fort was rebuilt and expanded, and eventually included a house for the fort commander, a chapel, barracks, and storehouses for supplies. Cobras Island; Forts and fortifications