Birkenhead is a north-western suburb of Adelaide 14 km from the CBD, on the Lefevre Peninsula, in South Australia, and lies within the City of Port Adelaide Enfield. It is adjacent to Peterhead, Exeter and Glanville. It is bounded to the south by the Gawler Reach of the Port River, to the north by Hargrave Street and in the west and east by the Outer Harbor railway line and the Port River respectively. It was laid out on section 700, Hundred of Port Adelaide by Thomas Elder and John Hart.Birkenhead Post Office opened around 1884.