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 UCC – 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 (€10).
The prison closed in 1923, reopening in 1927 as a radio station that operated until the 1950s. The Governor's House has been converted into a Radio Museum where, alongside collections of beautiful old radios, you can hear the story of Guglielmo Marconi's conquest of the airwaves.