O’Brien Castle

O'Brien's Castle on the left at Inisheer - © JUAN CARLOS MUNOZ
Note Traveler's Note
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Adresse Location:
Inisheer, (County Galway)

O’Brien Castle is a superb Irish fort now in ruins, located on the island of Inisheer, an island belonging to the Aran Islands. Built in the XIVth century, the castle suffered an important siege, then was destroyed during the Conquests of Cromwell. The castle is nowadays partially standing, and has an elusive charm, and most authentic!

History of O’Brien Castle

A Castle victim of a terrible siege, then of the Cromwellian Conquest.

O’Brien Castle was built in the 14th century for the O’Brien family, a powerful family who had already ruled the island of Inisheer for several years. The castle was inhabited by the clan for many years, until the castle was besieged in 1582 by another Irish clan: the O’Flahertys. This family is much more powerful than the O’Brien, and already reigns over certain regions of Connemara.

At the end of this siege, the O’Brien family confessed defeat and ceded the castle to the victors. But the O’Flahertys’ victory was short-lived. It was in the 17th century that the castle suffered another assault: that of Oliver Cromwell, who came to crush the Irish claims in 1649.

The fight is then terrible: the O’Flahertys don’t manage to control Cromwell’s troops, who don’t hesitate to mobilize all the possible artillery against the ramparts of the castle. Very quickly, the battle is lost for the Irish clan, and the castle is in ruins, ravaged by multiple cannonballs.

Since then, the castle has remained as it was, and has been registered with the Irish heritage as a major tourist site on the small island of Inisheer.

Visit O’Brien Castle

A Fort built on top of a hill, facing the ocean

The castle, although shaky, is accessible to visitors in some places, provided that extreme care is taken to avoid a massive landslide of the construction. It’s not worth the risk of getting hurt by being a little too adventurous… (And above all it would spoil your holiday)

To approach the O’Brien Castle, you will have to cross several dry stone walls, located all around the castle . These walls would be the remains of old buildings probably gathered around the fort… These would not have survived time, as well as the conquests of Cromwell, who ravaged the whole castle and its surroundings during the 17th century.

When you get close to the castle, we recommend the utmost caution: its stone walls are shaky, and the stability of the building is questionable …

O’Brien Castle
Practical information

Address Address:
Inisheer is accessible by ferry. These leave from Ros a' Mhíl (Connemara) and Doolin (Co. Clare), as well as from the other Aran Islands. The castle faces the ocean: impossible to miss!

Coordonnées GPSGPS:
53.062135, -9.519113

Duration of the visit Duration of the visit:
30 minutes
PricesPrices :


Opening hoursOpening hours:

every day from 9:00 a.m. to 5:00 p.m.

O’Brien Castle : the map

So much more to discover...