On my final day in Derry, a city barely inside the northwest edge of Northern Ireland, I hired a taxi to drive me past the city’s boundaries and across the United Kingdom’s border. Through the window, the Republic of Ireland was all endless rows of barley like coiled rosary beads. I wanted to see the Grianan of Aileach, a stone ringfort originally built almost fifteen hundred years ago by the Celtic king who then ruled Donegal’s hills.
