Fort Prinzenstein is a fort located at Keta, Ghana, which was used in the slave trade. Many such forts were built in Africa, but Prinzenstein is one of the few that lie east of the Volta River. Keta served as an open port until the Tema Harbour commenced its operation to the west in 1962. The fort has been designated a World Heritage Site because of its historical importance and testimony to the Atlantic slave trade.