County Tyrone (Irish: Contae Thír Eoghain) is the second largest of the nine counties of Ulster and the largest of the six counties of Northern Ireland. It has an area of 3,155 square kilometres (1,218 square miles). The county borders the Northern Ireland counties of Armagh, to the south-east, Fermanagh, to the south-west and County Derry to the north-east. The county also borders Lough Neagh to the east. The borders with the Republic of Ireland are County Monaghan to the south and County Donegal to the north-west.