This imposing former prison is well worth a visit, if only to get a sense of how awful life was for prisoners a century ago. An audio tour (€2 extra) guides you around the restored cells, which feature models of suffering prisoners and sadistic-looking guards. Take a bus to University College Cork (UCC), and from there walk north along Mardyke Walk, cross the river and follow the signs uphill (10 minutes).
The tour is very moving, bringing home the harshness of the 19th-century penal system. The most common crime was that of poverty; many of the inmates were sentenced to hard labour for stealing loaves of bread. Atmospheric evening tours take place every weekday at 5.45pm (€12, booking required).
The prison closed in 1923, reopening in 1927 as a radio station that operated until the 1950s. The on-site Governor's House has been converted into a Radio Museum where, alongside collections of beautiful old radios, you can hear the story of radio pioneer Guglielmo Marconi's conquest of the airwaves.