Dundanion Castle (Irish: Dún Daingean, meaning 'firm fortress')[1] is a Tudor tower house in the Blackrock area of Cork in Ireland.
[4][5] Though built on or close to the site of an earlier structure,[2] the existing limestone ruin dates to c.1564.
[1][7] Owing to later land reclamation, the castle is now located some distance from the waterfront of the River Lee.
[8] However an adjacent slipway demonstrates an earlier use,[8] and some sources ascribe the castle as William Penn's departure point on one of his voyages to the Americas ahead of the founding of Pennsylvania in the 1680s.
The castle is listed by Cork City Council as a protected structure (PS492),[10][11] and it is included on the Irish national Record of Monuments and Places (CO 074-049).