Armchair Archaeology: Ireland’s largest castle

Published: 24 Apr 2020

Welcome to the second edition of Armchair Archaeology! In this series we look at the famous and the less well-known sites in the Boyne Valley. Since the current restrictions mean we cannot go out and explore in person, let Boyne Valley Tourism take you on a virtual tour of some of our favourite sites. Today we'll be looking at Ireland’s largest castle, Trim Castle.


Trim Castle is the best preserved of the early Anglo-Norman castles in Ireland. Its history is interwoven with the story of how the Anglo-Normans came to Ireland in the late 12th century.

The Anglo-Normans came to Ireland on the invitation of an exiled Irish king, Diarmait Mac Murchada. One of the leaders of the invasion force was Richard de Clare, also known as Strongbow. This ambitious lord quickly established a large power base in Leinster, much to the alarm of his king, Henry II of England. To counter the power of Strongbow the king granted the former Gaelic kingdom of Midhe to his loyal lord Hugh de Lacy. Midhe became the County of Meath and de Lacy chose Trim as his headquarters in 1172.


The castle that we see today is the second castle built on the spot. Hugh de Lacy’s first castle was a wooden ringwork castle and this was immediately attacked and burned by Ruaidrí Ua Conchobair, the last High King of Ireland! De Lacy rebuilt the castle, this time in stone, and became a formidable fortress and symbol of English control in Ireland. See above an artist's impression how how Trim Castle would have looked in medieval times.

De Lacy’s son Walter de Lacy inherited the castle and from there it passed through his granddaughter to the de Geneville family. It then passed to the famous Mortimer family of England and Ireland before it was finally seized as a possession of the crown after the War of the Roses.

As you can see above Trim Castle’s main tower (keep) has a very unusual cruciform (cross-shaped) design. Normally the corner is the weakest part of a castle; Trim’s keep has twelve! It is believed by some that this design was inspired by castles built in the east during the Crusades. Both the de Lacy and de Geneville families had long crusading traditions.


Trim Castle remained in a state of ruin for many years until the 20th century when it was reused as the backdrop for several major movie productions. In Lee Marvin’s Second World War movie The Big Red One the castle doubled as a German castle but it was Mel Gibson’s Scottish epic Braveheart that drew the most attention. Trim Castle doubled for castles in Edinburgh and York and many locals were used as extras in the movie.

In the image below you can see a still from the movie: can you tell the real medieval structures from the fake ones?

After the movie was finished the OPW embarked on a major archaeological excavation and restoration process, before the castle was opened to the public once more. Nowadays it welcomes thousands of visitors every year. When you are next able to visit, don’t forget the Trim Visitor Centre beside the entrance to the castle. Here you can find out lots more information on the wonderful town of Trim and even take the Medieval Armoury Tour where you can step back in time to Medieval Trim and hold a real sword, try on a Norman helmet and feel real chainmail.


For more information on the medieval walled towns of Ireland and a FREE downloadable kids activity book see here.

Listen below to some wonderful audio on Trim Castle courtesy of Abarta Heritage.

Our thanks to Copter View for the amazing drone photos. We hope you've enjoyed this article on the mighty Trim Castle. 

Stay tuned for many more, and in the meantime stay home and stay safe.