grianan of aileach, ancient drystone ring fort, part of prehistoric structures complex, located on top of greenan mountain in

architecture prehistoric structures historical concentric inishowen landscape panoramic structure peninsula gaeltacht drystone mountain landmark building atlantic grianan aileach ancient complex located greenan donegal ireland scenery tourism tourist larger swilly meadow nature scenic temple palace travel circle europe cashel county lough orbit ruins rural stone irish grass drone derry green ring fort site view iron wild wall hill top sun age ely god