Ordnance Survey Maps: To obtain a list of townlands noted on a particular Ordnance Survey map you will need the OS map sheet number. You can obtain this by identifying in the database one relevant townland and taking note of its OS sheet number in column 1.
Counties and Towns: Since partition in 1922 various changes have occurred in county and town names. Modern-day Co. Laois was formerly Queens county and Co. Offaly was formerly Kings county. In addition, Co. Londonderry is also known as Co. Derry. Although not comprehensive, a list of changes of name for towns would include the town of Parsonstown, Co. Offaly now being known as Birr; Kingstown, Co Dublin, now being called Dun Laoghaire; and Queenstown, Co. Cork having reverted to Cobh, an Irish spelling of its original name, Cove. Also, Newtownbarry, Co. Wexford is now Bunclody; Maryborough, Co Laois is now Portlaoise; and Philipstown, Co. Offaly is now Daingean. In 1922 the Co. Meath town of Navan was renamed in Irish as an Uaimh, but as the change proved unpopular it was abandoned in 1971.
Poor Law Unions (aka Superintendent Registrar’s Districts): For an interactive map of PLU/SRDs showing boundaries visit this website. For a list of townlands which comprise each PLU/SRD visit this website. Also, for a map noting the District Electoral Divisions which comprise each PLU/SRD in 1935 (with revisions in 1961), follow these links: i) North-East Ireland; ii) North-west Ireland; iii) South-East Ireland; iv) South-West Ireland. For a key see top left-hand corner of the map for North-East Ireland.