Clan Rising
Castleknock Castle today

Ireland · Ruin

Castleknock Castle

Castleknock Castle is a ruined Norman castle on a low mound west of Dublin, Ireland, now on the grounds of St. Vincent's Castleknock College. The site is dominated by a polygonal keep and the remains of curtain walls and towers; two deep defensive ditches formerly surrounded the castle. Today only ruins survive, set among trees and grassy slopes.

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Photograph via Wikimedia Commons

Its prime

1300

Today

Ruin

As it stood in 1300

What Castleknock Castle looked like in its prime.

At its prime the castle was dominated by a roughly 24 m high polygonal stone keep attached to a large, low squat stone building, all built of grey coursed masonry. A continuous curtain wall, punctuated at intervals by smaller towers, enclosed an inner bailey; the whole was defended by two deep ditches cutting into the surrounding slope. Narrow slit windows, crenellated battlements and the angular polygonal silhouette of the keep defined the roofline, sited on a grassy mound with trees framing the site.

Its story

The story of Castleknock Castle.

After the Anglo-Norman triumph the knight Hugh Tyrrel was granted the barony of Castleknock, and built his castle there for its command over the route to Dublin. While it stood intact, the polygonal keep rose about 24 metres, with a large squat building attached and a curtain wall interspersed with towers, the whole further protected by two deep moats.

The Tyrrels held the barony in succession, Richard Tyrrel was the second Baron, and legend tells that a brother of the Baron, possibly Roger Tyrrel, abducted a woman and imprisoned her in the castle's turret. In a later war the Baron of Castleknock and his wife were taken prisoner, and the captured castle served as Edward's headquarters.

In 1834, forty acres of Castleknock including the ruins were sold to John McCann, a Vincentian friar, and the site is now St Vincent's Castleknock College, an all-boys Catholic school. On Windmill Hill, a small mound west of the campus, stands a water tower originally built as an observatory by a previous owner, Simon Guinn; trees screen the ruins from the road except in winter.

Step inside

9 places to explore in 1300.

The record describes 9 distinct spots at Castleknock Castle, including 2 interiors: small turret chamber, keep interior with ancient altar tomb. Create your own photoreal reconstruction and explore every one, more scenes means more rooms, more angles, and more of the place to stand in.

South approach on grassy slopeBase of the polygonal keep (exterior)Top of the keep / battlementsCurtain wall walkway between towersInner bailey / courtyardSmall turret chamberTwin defensive ditches (moats)View from Windmill Hill (west mound)Keep interior with ancient altar tomb

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Whose castle

Clans who held Castleknock Castle.

The families that held Castleknock Castle for a decade or more across its history, follow a name to its clan.

  • Tyrrel

    Granted to the knight Hugh Tyrrel after the Anglo-Norman conquest; his line held the barony of Castleknock.

Nearby

Landmarks within reach of Castleknock Castle.

Kilmainham Gaol, IrelandMuseumKilmainham Gaol5 km awayGlasnevin Cemetery, IrelandCemeteryGlasnevin Cemetery6 km awayGuinness Storehouse, IrelandMuseumGuinness Storehouse6 km away

Questions about Castleknock Castle

What is the history of Castleknock Castle?

Castleknock Castle was built after the Anglo-Norman conquest when Hugh Tyrrel was granted the barony of Castleknock. Its position commanded the route to Dublin. In 1317, Edward Bruce captured it and used it as his headquarters, but Scottish forces soon withdrew. The castle was later damaged by artillery during the War of the Three Kingdoms and dismantled after the war.

What is inside Castleknock Castle?

Inside Castleknock Castle, the documented remains include a small turret chamber and a keep interior containing an ancient altar tomb. The altar tomb, known as a cromlech, was discovered in 1861. The plot enclosed by the old castle walls is now used as a cemetery.

Why was Castleknock Castle built, and what was it used for?

Castleknock Castle was built to command the route to Dublin and formed a fortified stronghold. Its defences included heavy battlements and two deep ditches. Later, the site became part of St. Vincent's Castleknock College, while the land enclosed by the old walls is now used as a cemetery.

Where is Castleknock Castle?

Castleknock Castle is on a low mound west of Dublin, in Fingal. The ruins stand on the grounds of St. Vincent's Castleknock College, with Windmill Hill, a small mound, to the west of the campus. Trees surround the site and obscure views from the road except in winter.

Was Castleknock Castle ever attacked or besieged?

Castleknock Castle was attacked and captured more than once. General Monck’s English forces took it in 1642 with heavy cannon fire, and Irish forces retook it in 1647 after Owen Roe O’Neill’s siege. Earlier, in 1317, Edward Bruce captured the castle while travelling to besiege Dublin, but his forces vacated it the next day.

Which family or clan held Castleknock Castle?

The Tyrrel family held Castleknock Castle and its barony. Hugh Tyrrel was granted the barony after the Anglo-Norman conquest, and his line held it in succession. Richard Tyrrel was the second Baron of Castleknock.

What did Castleknock Castle look like in its prime?

In its prime, Castleknock Castle had a roughly 24-metre-high polygonal stone keep attached to a large, low squat stone building. Grey coursed masonry formed the main structures. A curtain wall with smaller towers enclosed the inner bailey, while two deep defensive ditches cut into the grassy mound. Narrow slit windows and crenellated battlements defined the angular silhouette.

Is Castleknock Castle still standing, or is it a ruin?

Castleknock Castle is a ruin, with only parts of the medieval complex surviving. The polygonal keep, attached building, curtain walls, towers and two defensive ditches were damaged, particularly by artillery during the War of the Three Kingdoms. After the war, the Commonwealth government ordered the battered castle to be dismantled.

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