The architect of Union County's first courthouse has remained anonymous but may have been Christopher Seebold II, who donated the lot and served as county treasurer and justice of the peace. Built with local clay brick laid in Flemish bond, the former courthouse resembles a Georgian house with a fanlight over the arched entrance and double chimneys on the gable ends. At the rear of the building, a two-story polygonal apse with a hipped roof recalls the old Delaware County courthouse (
DE1) and probably refers to other now demolished courthouses of the post–Revolutionary War era. After the county seat moved to Lewisburg, the courthouse was renovated into an elementary school, a process that required gutting the interior and replacing the Georgian cupola with a bulky bracketed Italianate tower. The Union County Historical Society has restored the courthouse and the building serves as the post office and home of the Courthouse Museum.