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. Admission for access to the visitor centre and fort are €3 for adult, €2 for senior citizen and €1 for student and child. There are also highly knowledgeable tour guides available for tours and to answer any questions you may have.
The Black Fort
This fort is also located on the edge of a high cliff, it’s situated at the southern side of Inis Mór. The construcion consists of a extended part which was defended by a bended wall and a “chevaux de fries”. There are still remains of stone houses visible at the interior. There are also a series of long rectangular buildings next to the extended part of the fort, these were probably used as cattle yards in a later period. This type of fort dates back to the Iron Age and the construction can be situated between 200 BC and 500 AD. Because archaeologists found some pottery here, they believe that it’s possible that there was already a small settlement there before the fort. The integration of the houses on the inner face of the enclose suggests that the fort was occupied in the early Medieval period (9th - 10th century).
Dún Eochla is a superb stone ring fort located at the highest point on Inishmore in the Aran Islands. The inner walls measure approximately 5 metres in height, and over 3 metres in depth. This fort deserves far more attention than it gets with it’s fantastic location and remarkable condition, but is overlooked because of the popularity of the nearby Dún Aengus. It has been estimated that Dún Eochla was built sometime between 550 and 800 A.D. Like most stone forts, this one is a bit over restored, but I am very impressed by the dry stone walling. While some web sites may reference a stone hut in the enclosure, the structure in the centre is more likely a repository for stones left over from the restoration.
The Seven Churches
Situated 3km north-west of Kilmurvey, the miscalled - Seven Churches - mark an ancient site dedicated to Saint Breacan. The name is loosely applied to the remains of two small churches, Teampall Bhreacain and Teampaill an Phoill. Close to the churches, on the south-west, is Leaba an Spioraid Naoimh (bed of the Holy Spirit), a penitential station with fragments of a figured high cross. Nearby, to the south-east, is Leaba Bhreacain, another station. To the north of Leaba an Spioraid Naoimh is an early cross-slab and north of the church are the ruins of late 15th century monastic houses. In the south-east corner of the churchyard are some early graves and also prostrate on the rock, in the fields to the south-east is a fractured high cross with elaborate interlacing, etc.