Round House, Fremantle

Perched above the harbour at Fremantle, this twelve-sided limestone gaol is the oldest surviving public building in Western Australia, completed in 1831 soon after the founding of the Swan River Colony. Its cells radiate around a central courtyard, and a tunnel beneath once let whalers reach the beach below. A time-ball and cannon on the ramparts still mark one o'clock each day for visitors. Later used to detain Aboriginal prisoners before transport to Rottnest Island, the building carries a difficult history.