Built in 1532 to watch over the main entrance to the harbour, this tower was topped in 1651 with a small wooden steeple. On the back of the tower is a sculpture of a unicorn, the town's symbol. Since 1968, a trio of ship's boys (a bronze sculpture by Jan van Druten) has looked out over the harbour from the base of the tower. They represent the heroes of the children's book by Johan Fabricius, dedicated to Bontekoe.