St Columb Major is situated in the Deanery and Hundred of Pydar. It is bounded on the North by Little Petherick and St Issey, on the East by St Wenn, Roche and St Dennis, on the South by St Enoder and Colan, and on the West by St Columb Minor, Mawgan-in-Pydar and St Ervan. A large area of North Cornwall bears the name of St Columb; it is divided between the parishes of St Columb Major and St Columb Minor. Until relatively recently these were known as Higher and Lower St Columb. The principal villages in the parish are: Glivin, Halloon, Rosedinick, Rosevanion, Ruthoes (or Ruthvos), Tolskiddy, Tregamere, Tregaswith, Tregatillian, Trekenning, Trevarron, Trevolgas and Trugo