County Offaly population. It is the largest county by area and the third largest by population in the Midlands. Lusmagh Tullamore is the county town and largest town in Offaly and is the 30th largest in Ireland. Offaly borders seven counties: Galway, Roscommon, Tipperary, Laois, Westmeath, Kildare and Meath. The Slieve Bloom Mountains are in the southern part of the county on the border with County Laois. Offaly has the 24th highest county peak in Ireland. The highest point is Arderin () in the Slieve Blooms at . The Slieve Bloom Mountains contain the county's highest points including Stillbrook Hill and Wolftrap
County Offaly out across the county with the Bog of Allen extending into four other counties. The county consists of approximately 42,000 hectares of peatlands which is 21% of Offaly's total land area. Offaly contains approximately of forest and woodland area, which only amounts to 4.5% of the county's land area. This includes woodlands within the Slieve Blooms and the Lough Boora Parklands. Roughly 75% of Offaly's forested area is Conifer High Forest. The following are the historical baronies located in County Offaly: One of the earliest known settlements in County Offaly is at Boora bog which dates back to the Mesolithic