sentences:  Glencastle is a mountain valley which used to be known as the gateway to the Mullet Peninsula.In the middle of this glen stands an ancient fort called "Dun Donnell" or the fort of Domhnall.Domhnall was, according to legend, of the Gamanraige tribe and an ascendant of an Ailill Finn the husband of Flidhais and involved in the tale of Táin Bó Flidhais.