Inishmore (or Inis Mórin Irish) is the largest of the three Aran islands. Its 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. Saint 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 Saint Soorney's Church. To the west of Kilronan is the church of Saint Enda, the saint most closely identified with the spread of Christianity on Aran. Kilmurvy is the other main village on Inishmore; it lies about 7km west of Kilronan, and in its vicinity is the Church of Saint Colman MacDuagh, and the Church of the Saints. Undoubtedly the most famous and impressive site on Inishmore is the great stone fortress of Dun Aonghasa -- the largest of the prehistoric stone forts of the Aran Islands. It is perched spectacularly on the edge of a sheet 100m (300 ft) cliff that falls away into the Atlantic Ocean. It is enclosed by three massive dry-stone walls and a "chevaux-de-frise" consisting of tall blocks of limestone set vertically into the ground to deter attackers. The fort is about 900 metres from the visitor centre and is approached over rising ground. Wheelchair access is available to the visitor centre, but not to the fort. The admission fee is EUR 2.00 for adults, EUR 1.25 for groups & senior citizens, EUR 1.00 for children and there is a family rate of EUR 5.50.