Walking up along Harbour View from the Bench to the Cathedral Walk, provides a panoramic view of the harbour. Its centre is dominated by Spike Island. The military fortifications on the island were upgraded in 1790 and adopted for use in 1847 as a holding prison for convicts who were bound for 'transportation' to Australia. Prior to this, convicts had been kept in chains in prison ships known as 'hulks'. These were anchored in the harbour for months and sometimes years waiting until they had a full cargo before undertaking the torturous journey. During these protracted periods the convicts were kept in chains at all times. John Mitchell, a famous Irish patriot, writer and poet was held on Spike Island in 1848 before being transported to Australia.