Dungannon is a town in County Tyrone, Northern Ireland. It is the second-largest town in the county and had a population of 16,282 at the 2021 Census. The Dungannon and South Tyrone Borough Council had its headquarters in the town, though since 2015 the area has been covered by Mid-Ulster District Council. For centuries, it was the 'capital' of the O'Neill dynasty of Tír Eoghain, who dominated most of Ulster and built a castle on the hill.