A Brief History

Although formal records do not begin until about the middle of the 16th century, there are indications that a fortification of one type or another has stood on the tiny promontory jutting out into Cork Harbour since Anglo-Norman times. In the late 16th century, the citizens of Cork appealed to Queen Elizabeth I to construct a fort at Blackrock to "repel pirates and other invaders".
In 1722 the old four-Storey tower was destroyed by fire and the new one was rebuilt with an octagonal room topped with a cupola.
Throughout this period, the castle was used by Cork Corporation for banquets and "convivial gatherings"- some associated with the custom of "throwing the dart". This custom, dating to at least the 18th century, was held every three years in August, and involved a dart (an arrow about four feet long) being thrown by the mayor from a boat, to indicate the Corporation's jurisdiction over the harbor.
“Alluding to the lantern on the castle that served as a beacon of comfort to the fishermen abroad on Lough Mahon in the darkness of night”
Henry Bennett
Local poet and lawyer
Shortly after he penned those lines, however, It wasn't the beam from the lighthouse that lit up the surrounding area, but the castle itself. For early on The Morning of Tuesday, February 27, 1827, Blackrock Castle burned to the ground in a spectacular blaze.
The rebuilding began at the direction of Mayor Thomas Dunscombe in 1828 and was completed in March 1829. The Architects added three additional Storeys to the original tower and rebuilt the out-buildings. The architects were George Richard Pain and James Pain. The neo-gothic complex of buildings around a courtyard is essentially what remains today.
The present castle consists of a large circular tower with crenellated parapets resting on large corbels. It incorporates portions of the walls of the second castle which were strong enough to withstand the Impact of Cannon balls. On its eastern side it is joined to a cylindrical tower rising several feet above the main Structure. At the side of this tower is a Watergate leading to a slipway.