Completed in 1831, this 12-sided stone prison is WA's oldest surviving building. It was the site of the colony's first hangings, and was later used for holding Aboriginal people before they were taken to Rottnest Island for incarceration. At 1pm daily, a time ball and cannon-blasting ceremony just outside reenacts a historic seamen's alert. Book ahead to fire the cannon.

　　To the Indigenous Noongar people, this is a sacred site because of the number of Aboriginal people killed while incarcerated here. Freedom fighter Yagan was held here briefly in 1832. Beneath is an impressive 1837 Whalers' Tunnel carved through sandstone and used for accessing Bathers Beach, where whales were landed and processed.