I have done several posts regarding the Port Elizabeth Harbour defenses erected around the city during World War II, but just to recap in case you haven't seen any of them. Before the Second World War the Port Elizabeth Harbour actually had no defense in place except for Fort Frederick which was built in 1799 to guard the original landing place in the early days. In 1942 it was decided to put harbour defenses in place at all South Africa's harbours. In Port Elizabeth Three Fortress Observation Posts (FOPs) were built at Amsterdam Hoek (Bluewater Bay), Seahill (Cape Recife) and Skoenmakerskop, together with a Port War Signal Station next to Cape Recife lighthouse. These three along with the Algoa Battery building in Humewood and the Battery Observation Post on Brookes Hill had to keep a constant lookout for approaching ships, submarines and planes.
If you click on the links you'll see the posts featuring these buildings. That is all but the Algoa Battery which is situated on the army base on the PE beachfront. Its not the easiest place to visit although I get to see it from behind the fence every morning on my way to the office. Heading out to a meeting I decided to snap a picture of it from the road until a better opportunity presents itself some day. The lookout tower is a slightly more modern version although not in use anymore either.