Desmond Castle is a four-storey tower house on Cork Street, built around 1500 by the Earl of Desmond as a customs house for the busy medieval port. It is one of the best-preserved examples of this Irish architectural type, and its history since construction has been eventful enough to merit its own museum. Today it houses the International Museum of Wine, which tells the story of the Irish diaspora's role in establishing vineyards across Europe — particularly in France, where Irish emigré families named Lynch, Barton, and Hennessy became major figures in the Bordeaux and Cognac trades.
The museum is small but well-curated and opens a genuinely unexpected angle on Irish history. The castle is a short walk from the harbour, and the views from the upper floors over the town's rooftops are good.