Desmond Castle was built as a custom house by the Earl of Desmond c. AD 1500. Desmond Castle has had a colorful history, ranging from Spanish occupation in 1601 to use as a prison for captured American sailors during the American War of Independence. Known locally as 'The French Prison' after a tragic fire in which 54 prisoners, mainly French seamen, died in 1747. The castle was also used as a borough jail from 1791 to the onset of the Great Famine when it was used as an auxiliary workhouse tending to the starving populace.