Inis Mór is the largest of the three islands. It’s principal village is Kilronan where there is a good, deep harbour.
An excellent Visitor’s Centre, Ionad Arainn, provides a solid introduction to the history and culture of the island. Sites to see include the interesting remains of Arkin’s Castle, a Cromwellian fort that maintained a garrison during the 17th and 18th centuries. St. Ciaran’s Monastery, east of the village, where can be seen also several early cross-slabs, pillars and a holy well dedicated to the early saint. Also in this locality is the very early St. Soorney’s Church.
To the west of Kilronan is the church of St. Enda, the saint most closely identified with the spread of Christianity on Aran. Kilmurvy is the other main village on Inishmore; it lies about seven kilometres west of Kilronan, and in its vicinity is the Church of St. Colman Macduagh, and the Church of the Saints. Undoubtedly the most famous and certainly the most impressive site on Inishmore is the great stone fortress of Dun Aonghus, perched dramatically on the edge of a sheet 300 ft cliff that falls away into the Atlantic Ocean. Altogether this massive fortress covers almost 11 acres and consists of three enclosures constructed of large limestone blocks