Back along the base of Inishowen to Derry, Elagh Castle is visible among the foothills. What remains is very fragmentary and looks like a circular tower house but some have speculated that there was once a second tower making a gatehouse similar to that at Harry Avery’s Castle in Co Tyrone. The castle was occupied by the O'Doherty’s at the time of the Ulster Plantation in the early Seventeenth century but the site appears have been occupied as a major defensive position since at least the early medieval period. Recent archaeological excavations discovered a ditch from this period and those involved have speculated that this, rather than Grianan, may have been the location of Ailech, one of the great royal sites of Ireland.
