Mahee Castle – A Fortified Tower House at Strangford Lough

Published by P&P on

Mahee Castle Background


Visitors to the impressive Nendrum Monastery site will pass the ruins of Mahee Castle on the same stretch of road. Although a small building, the castle is worth a short visit in recognition of its history and scenic setting.

Mahee Island Location
Mahee Island Location –


Mahee Castle is actually the ruins of a tower house on Mahee Island, one of the larger islands, in Strangford Lough. It was built on the north-east side of the isle in 1570 by Englishman Captain Thomas Browne. However, recent excavations suggest there may have been a building on this site even earlier.

The name Mahee comes from St Mochaoi, who founded Nendrum monastery which is just a a short walk from the tower house.

The castle is situated at the head of a causeway, the only land access to the island. Its location explains its defensive function. The Bishop of Down petitioned Browne to construct the tower house here, as it was near the border of two rival territories, Clandeboye to the north and Dufferin to the south.

Mahee Castle and Nendrum Locations
Mahee Castle and Nendrum Locations –

Rival Territories

Clandeboye from the Gaelic Clann Aodha Bui ‘family of Hugh the Blond’ occupied what are now parts of north county Down and south county Antrim. They were descended from Hugh Boy O’Neill, a king of county Tyrone.

The Dufferin lands abutted Clandeboye on its northern border at Strangford Lough. At one time the area was ruled by the MacCartan sept but at this time was in the hands of the White family, originally from county Meath.

Mahee Castle
Mahee Castle

Mahee Castle Architecture

The foundations of the tower have revealed a man-made terrace constructed to support the building. It is actually situated on a drumlin, a smooth hill formed during the ice-age. The added height would have made the castle even more imposing to an enemy.

The architecture of the building reflects its military purpose. It is rectangular in shape, 40ft by 22ft. On the ground floor are two small rooms, the larger of which has a semi-circular vaulted ceiling. On the west wall is an arched doorway, which is thought to have connected with the kitchen.

Mahee Castle doorway
Mahee Castle doorway

The house was originally composed of three storeys with the living room and bedrooms on the upper levels. All the rooms only had small slit windows for safety sake. Most tower houses had chimneys with open fireplaces and built-in latrines. The gabled roofs were thatched or slated with a walkway and battlements for sentries to keep look-out.

The entrance is on the north edifice. This was guarded with a machicolation or murder-hole. This is an opening in the ceiling; whereby defenders could pour boiling water, stones, hot tar and other substances on invaders.

Mahee Castle arched entrance
Mahee Castle arched entrance
Mahee Castle murder hole
Mahee Castle machicolation or murder hole

The tower house was protected by its lakeside location and to the south-west by a bawn, a strong stone defensive wall. By the early seventeenth century Mahee Castle had been abandoned and fallen into disrepair. A lot of its masonry was used in the construction of the current road.

Castle and Lough
Castle and Lough

Mahee Castle Today

In the 1920’s H C Lawlor, under the auspices of the Belfast Natural Historical and Philosophical Society, carried out surveys and restoration work at the castle.

“In 1922 the ruin was in great danger of further destruction from ivy growing through the walls; many cracks were showing, and any storm might have almost completed its destruction. All the ivy has now been cut out, the cracks and loose stones grouted with cement, and a strong buttress built under the N E corner, which had been deeply under-mined; the tops of all the walls have been made water-tight by cement, so that the ruin may now stand safe for centuries”

H C Lawlor 1925
Mahee Castle Ruins
Mahee Castle Ruins

More recent archaeological digs have uncovered knives, pottery shards, animal bones and shells spanning several centuries.

In Conclusion

Mahee Castle’s proximity to Nendrum Monastery makes it an interesting stop on the way to the beautiful Monastery site. The Strangford Island setting is particularly scenic when our fickle weather allows sunshine and blue skies – not the case for this visit unfortunately…


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Location & Parking

Location: 20 Mahee Island, Comber, Newtownards, County Down BT23 6EP

Mahee Castle is free to visit. There is a small free carpark further along the road at the Nendrum Monastic site.

Related Post

Nendrum Church & Tower
Nendrum Church & Tower

Nendrum – An ancient Monastery with the oldest tide-mill in the world

The long history of Nendrum Monastery features St Patrick, Viking attacks, settlement by Benedictine monks and the world’s oldest tide-mill

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