We often will turn to the first edition Ordnance Survey maps to explore the townlands of our ancestors ... Figure 2: The c.60,000 townlands of Ireland visualised in number by map sheet.

But on January 1st, 1922, the OS of Northern Ireland was established in Belfast, while on April 1 st that year the OS of the Free State came into being, known as Ordnance Survey Ireland.

The OS200-Digitally Re-mapping Ireland’s Ordnance Survey Heritage project has compiled historic maps, texts, archaeological and toponymical material, including local customs, place names and ...

OS Maps app has supported outdoor enthusiasts across England, Scotland and Wales for over seven years – and Northern Ireland walkers will now be able to use the app here.