Information about O'Brien's Castle

Information from O'Donovan's Field Name Books

Standard Name:
O'Brien's Castle
Irish Form of Name:
Civil Parish:
Other Forms of the Name with authority source (if provided) in italics:
O'Brien's Castle
East Island Castle
Innisheer Castle Local name
See my letter J.O'D
Ruins of an old castle said to have been built by the O'Briens in the 14 century and reduced in 1652 by the Parliamentary forces.
In Innisheer townland.
Information from the Ordnance Survey Letters:
The Ordnance Survey Letters are letters between John O'Donovan and his supervisor, Thomas Larcom, regarding the work of compiling the Field Books. These letters provide further discussion on many of the places listed in the Field Books.
References to this place can be found in the following letter.
  • Volume 3 page 265 to page 266

Townland Information

What is a townland?:
A townland is one of the smallest land divisions in Ireland. They range in size from a few acres to thousands of acres. Many are Gaelic in origin, but some came into existence after the Norman invasion of 1169
O'Brien's Castle is in Inis Oirir (Colgan) townland.