Eldon Hill is a hill in the Peak District National Park in the county of Derbyshire, England, southwest of the village of Castleton. It is a limestone hill whose pastureland is used for rough grazing, although a large proportion has been lost to limestone quarrying. It lies within the Castleton Site of Special Scientific Interest. Eldon Hill was formed when a bed of pure limestone was squeezed and upfolded by geological forces to form a dome; it is the highest limestone hill north of the River Wye.