The Corporation of Cork City in Ireland (again) took possession of the newly constructed Blackrock Castle, 192 years ago on 3 March 1829.

Blackrock Castle is a castellated fortification located at Blackrock Village, about 2 km from Cork City centre on the banks of the River Lee in Ireland. Originally developed as a coastal defence fortification in the 16th century to protect the upper harbour and port, the site now houses an observatory, visitor centre and restaurant.

It is impossible to state precisely when the original fort was constructed on the site of the present Blackrock Castle. However, a document published in the Calendar of State Papers, dated 13 January 1600, indicates that the first fortification was constructed by the citizens circa 1582 and another dating from before 1585, is a petition to the Queen of England, in which it is stated that Cork has 'a fort called Blackrock' maintained by the citizens 'with artillery to resist pirates and other invasion'.

Around 1600, a round tower was constructed to safeguard against pirates "carrying away" vessels entering the harbour. The earliest elements of this structure remaining today are a circular tower on the water's edge, 10.5m in diameter, with walls 2.2m thick.

Lord Deputy Mountjoy took possession of the site in 1604 and either reconstructed the old fort or erected a new one. In 1608, the Charter of James I returned the castle to Corporation ownership. The building had a beacon, lit by turf, to guide shipping. The castle is later referred to in the Council Book of Cork in 1613 and 1614.

In 1722 the old four-storey tower was destroyed by fire and a new castle, a circular tower, was constructed by the citizens at a cost of ￡296. Later an octagonal-shaped room with a cupola was added to the top of the tower.

As the danger of attack by foreign forces or pirates receded the castle was, on occasions, rented to individuals. Throughout this period, the castle was used by the 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 harbour. The building was, however, used principally as an Admiralty Court.

Every third year, on 1 August, the mem-bers of the Corporation set out from the castle down river to the mouth of the harbour for the function of 'Throwing the Dart', the Mayor entertain-ing his guests in a lavish manner on their return from the ceremony.

Following a banquet, the castle was destroyed by fire in 1827. 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 new building cost the City of Cork ￡1,000. The architects were James and G.R. Pain, who were responsible for other public buildings around Cork at the time. The neo-gothic complex of buildings around a courtyard is essentially what remains today.

The castle entered private hands and for a time in the 20th century was used as a private residence, offices, rowing club headquarters, and restaurant. The building was reacquired by Cork Corporation in 2001, and work commenced on renovating and re-purposing the complex as an observatory and museum. The Castle was redeveloped under a joint venture between the City Council and Cork Institute of Technology. Opened in 2007, the "Cosmos at the Castle" project was intended to create a "centre for scientific research, outreach and communication". The castle's observatory houses an interactive astronomy center which is open to the public, and has exhibits including a "tour of the universe" and a radio telescope that beams messages composed by school groups towards nearby stars. The castle also houses labs staffed by astronomical researchers from Cork Institute of Technology.

The Corporation of the City of Cork took possession of the new Blackrock Castle on 3 March 1829.