Carrigrenane, Little Island, Co Cork  

Bence-Jones, Mark. A Guide to Irish Country Houses (originally published as Burke’s Guide to Country Houses volume 1 Ireland by Burke’s Peerage Ltd. 1978); Revised edition 1988 Constable and Company Ltd, London. 

p. 59. “(Bury/IFR; Sullivan/IFR) A pleasant square late-Georgian house of two storeys over a basement on a promontory jutting out into Lough Mahon. Perron in front of entrance doorway with double steps and simple railings, now partly obscured by porch. Compact but spacious interior; two drawing rooms en suite. Castellated tower by water’s edge. A seat of the Bury family. Occupied in 1^st half of C19 by John M. Ashlin, who was born here 1837. In recent years the home of the late Judge D.B. and Mrs Sullivan.”

https://www.castles.nl/carrigrenan-tower

Carrigrenan Tower, lies on Little island in Cork Harbour, in County Cork in Ireland. 

I was not able to find any historical information about this tower. Although it is often called a castle on the internet, I don’t think it is. 

Carrigrenan Tower is situated on the former grounds of Carrigrenan House, on the shore of Lough Mahon. This house stood on the site of the waste water plant that now occupies most this southern peninsula of Little Island. In the planning documents of this plant it is called an ‘ornamental tower’. So, I guess this was a folly or lookout tower of the owners of Carrigrenan House. If that is the case, then the tower would probably have been built somewhere in the 19th century. 

The ruin of Carrigrenan Tower is freely accessible. A nice tower on a very nice location. 

[note, from David Hicks, Irish Country Houses, Portraits and Painters. David Hicks. The Collins Press, Cork, 2014. 

 p. 23: George Coppinger Ashlin, an architect born at Carrigrenane House in Cork in 1837; in 1856 he became a pupil of Edward Welby Pugin with whom he eventually went into partnership. Ashlin was given responsibility of establishing a Dublin branch of the partnership and to look after the Irish commissions. His portfolio of work was dominated by a large number of churches, convents and schools and he was also responsible for the extension to Tulira Castle for Edward Martyn’s mother in Galway in the 1880s.