This urban tower house, now operating as Dalkey Castle and Heritage Centre, once served as the town hall and remains one of the finest examples of medieval defensive architecture in the area. Built from roughly coursed granite masonry with dressed stone quoins at the corners, the rectangular tower rises three storeys high, topped by a vault above the ground floor.

The building’s defensive past is evident in its construction; a projecting stair tower in the southeast corner extends above the parapet level, whilst the interior reveals a barrel vaulted ground floor chamber running east to west. Though visitors today enter through a late round arched doorway on Castle Street’s south side, the original entrance was actually on the north, where remnants of the original staircase can still be found. A 1765 drawing by artist Beranger shows this south entrance as it appeared then, damaged and blocked up, with another flat arched entrance visible on the eastern side.

Inside, the tower tells its own story of adaptation through the centuries. The ground floor chamber, lit by a deeply splayed embrasure to the east and a tall single opening in the southwest, retains its medieval character with floor corbels visible in the upper northeast corner wall. The first floor, measuring 10.6 metres long by 5.95 metres wide, was later remodelled as a council chamber complete with wood panelling and double light windows in the south wall; a large fireplace was inserted into the southern wall during this renovation. The second floor features a round arched window at the western end, whilst a more recent parish hall has been constructed against the tower’s northern wall, showing how this medieval structure continues to serve the community today.