This small, squat stone fortress doesn’t really look like a castle, in part because it sits incongruously half way up a residential street. Built around 1500 as the Customs house for Kinsale Harbour, in the late 17th century it was turned into a prison—at which time its history took several dark detours, including a fire that gutted the building in 1747, roasting alive the 54 French soldiers imprisoned within. Later, during the potato famine, it was used as a workhouse. Inside is an unusual little museum, which tells the extraordinary tale of the Irish exiles who helped transform the global wine trade from the 17th century onward.