O'Brien's Castle, Aran Islands Travel Guide

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Explore the historic O'Brien's Castle on Inisheer: a 15th-century tower house with stunning views and a rich, turbulent past. A must-see on the Aran Islands.

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O'Brien's Castle

Perched atop Inisheer, the smallest of the Aran Islands, O'Brien's Castle is a 15th-century tower house built on the site of a much older ringfort. Also known as Furmina Castle, it offers stunning views and a glimpse into the island's rich history.

A brief summary to O'Brien's Castle

Oir, Inisheer, Inisheer, Co. Galway, IE

From Eve

Know before you go

Hi, I'm Eve. Here are a few practical things to know before exploring O'Brien's Castle.

Wear comfortable shoes as the terrain around the castle can be uneven and rocky.
Visit early in the morning or late afternoon to avoid crowds and for better lighting for photographs.
Bring a camera to capture the stunning panoramic views from the castle.

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Getting There

Walking

From the Inisheer ferry terminal, O'Brien's Castle is approximately a 15-minute walk. Follow the local signs towards 'Caisleán Uí Bhriain'. The route involves a gradual uphill walk. The path is well-trodden but can be uneven in places. No costs are associated with walking to the castle.

Discover more about O'Brien's Castle

O'Brien's Castle, also known as Furmina Castle or Caisleán Uí Bhriain in Irish, stands as a striking ruin on Inisheer, the smallest of the Aran Islands. This 15th-century tower house was strategically constructed by the Clann Teige, a branch of the powerful O'Brien family, atop Dún Formna, an ancient ringfort dating back to between 500 BC and 100 AD. The location was chosen for its commanding views of Galway Bay and the mainland, allowing control of shipping routes and serving as a stronghold.The castle's history is marked by conflict. In 1582, it was seized by the O'Flahertys of Connemara, rivals of the O'Briens. In 1652, during the Cromwellian conquest of Ireland, Oliver Cromwell's army captured and deliberately damaged the castle to prevent its further use as a fortification. Since then, it has remained a ruin, a testament to the turbulent times.Today, O'Brien's Castle is a National Monument of Ireland. Visitors can explore the remains of the rectangular donjon (keep), which once had four stories. The original entrance was on the first floor, accessed by an external wooden stairs. The first floor served as a great hall, with mural stairs leading to the parapet. The ground floor was a basement with three vaulted chambers. Look for the corbel of a bartizan (a small projecting turret) with a human face carved into it. From the castle, enjoy panoramic views of Inisheer, the other Aran Islands, the Clare coast, and the Cliffs of Moher.