Calmore (from Irish An Coll Mór, meaning 'the great/large hazel'[2]) is a townland lying within the civil parish of Kilcronaghan, County Londonderry, Northern Ireland.

Local traditions however picked up by the Ordnance Survey Memoirs of 1836-37 state that it was his father, Shane More O'Hagan, who built it.

Shane More O'Hagan is noted as being the proprietor of the Drapers Proportion in this area together with other tracts of land, including ten townlands in Ballynascreen and Lough Insholin [sic], the heart of a large territory of the same name.

[5] The Ordnance Survey Memoirs note that in neighbouring Moneyshanere, a battle was said to have been fought between the O'Hagans who are stated as ruling Tobermore and the O'Neills of Tyrone, who are said to have come rampaging down from Ballynascreen.

[5] During its control by the O'Hagans, Calmore Castle was considered "once a place of very considerable strength, which commanded the mountain passes, and the fords of the Moyola".

[5][7] A tradition is recorded claiming that two years after it was burnt down, the very person who led the party and was the first to throw a sheaf of burning straw into the rooms, came begging to the windows of the partly repaired building.