Harrodsburg is a home rule-class city in Mercer County, Kentucky, in the United States. It is the seat of its county. The population was 8,340 at the 2010 census.Although Harrodsburg was formally established by the House of Burgesses after Boonesborough and was not incorporated by the Kentucky legislature until 1836, it is usually considered the oldest city in Kentucky and has been honored as the oldest permanent American settlement west of the Appalachians.